The following is section 32 of chapter 27 of Orthodox Catechism. I assume it won't have the proper formatting once I paste it, nor the footnotes. I am therefore going to italicize the long quote from St. Makarios of Alexandria so that it will at least be somewhat sensible:
32. Why does the Church hold the funerary and memorial services on the days that it does, namely the 3rd, 9th, and 40th days after repose?:
The answer to this question comes from the Life of St. Makarios of Alexandria:
--When, on the third day, the body is brought to the Temple, the soul of the dead man receives from his Guardian Angel relief from the grief which he feels upon parting from his body. This he receives because of the oblation and praise that are offered for him in God's Church, from which there arises in him a blessed hope. For during the space of two days the soul is permitted to wander at will over all the earth, with the Angels that accompany it. Therefore the soul, since it loves its body, sometimes hovers around the house in which it parted from the body; sometimes around the coffin wherein its body has been placed: and thus it passes those days like a bird which seeks for itself a nesting-place. However, the beneficent soul wanders through those places where it would perform deeds of righteousness.
On the third day He who rose from the dead commands that every soul, in imitation of his own Resurrection, shall be brought to heaven, that it may do reverence to the God of all. Wherefore the Church has the blessed custom of celebrating oblation and prayers on the third day for the soul.
After the soul has done reverence to God, He orders that it shall be shown the varied and fair abodes of the Saints and the beauty of Paradise. All these things the soul views during six days, marveling and glorifying God, the Creator of all. And when the soul has beheld all these things, it is changed, and forgets all the sorrow which it felt in the body, unless it is guilty of sins in which case, at the sight of the delights of the Saints, it begins to wail, and to reproach itself, saying: 'Woe is me! How vainly did I pass my time in the world! Engrossed in the satisfaction of my desires, I passed the greater part of my life in heedlessness, and did not obey God as I should have so that I too might be granted these graces and glories. Woe is me, poor wretch!'
After having thus viewed all the joys of those who are just for the space of six days, the Angels lead the soul again to do reverence to God. Therefore, the Church does well in that she celebrates the service and oblation for the Soul on the ninth day.
After its second reverence to God, the Master of all commands that the Soul be conducted to Hell [Hades], and there shown the places of torment, the different divisions of Hell [Hades]; and the various torments of the ungodly, which cause the souls of sinners that find themselves therein to groan continually, and to gnash their teeth. Through these various places of torment the soul is borne during thirty days, trembling lest it also be condemned to imprisonment therein.
On the fortieth day, the soul is again taken to do reverence to God: and then the Judge determines the fitting place of its incarceration, according to its deeds. Thus the Church does rightly in making mention, upon the fortieth day, of the baptized dead. (St. Makarios of Alexandria—from the Life of the Saint, the answer which the Saint received upon asking the angels which accompanied him why the Church celebrated religious services upon the third, ninth, and fortieth days after a death)
This passage, of course, refers to the soul's journey after death. This ‘journey’ of the soul (Gk. psyche) has to be understood within the context that the soul physically is immediately in God’s presence already, for there is no place that He is not, and that the soul is already beginning the foretaste of bliss or torment. It uses much symbolical language, and although not a dogmatic pronouncement of the Church, if understood correctly conveys truth. One should keep in mind, however, that the soul does not perceive time in the same way once it is reposed.
St. Makarios roams the earth for a few days, and then for six days encounters the “pre-Judgment throne experience” of the abode of the Creator of all who created in the same amount of days as the experience (six). Then for thirty days is driven into the wilderness of Hades, which is the 'abode' of the dead before the final judgment. We are informed by the book of Revelation that at the final Judgment, Hades will be cast into the eternal hell (Gehenna) of fire, and therefore since sufferings also occur in Hades, it is also accorded the name 'hell' in many languages, since eternal hell is the final end of Hades.
After the 40th day, God determines the soul's appropriate place of 'incarceration' in the intermediate state. The Lord calls the intermediate state of the abode with God “Paradise,” and in another place “Abraham’s Bosom.” The other abode is Hades. This is not the full eternal reward or condemnation that will be encountered at the Last and great Day of Judgment, but rather a partial judgment based upon God's foreknowledge of the future state of the soul and the final judgment. We therefore continue to pray for the soul after the repose of the person, since its end will not ultimately—from our point of view in time--be determined before the rest of humankind on the Last Day. At the memorial services, often either kollyva or bread is brought as a type of prayer-act of the Church, in hopes that the soul will stand well in the resurrection of the dead.