In the next life, spirits converse with each other the same way we do on earth. Good spirits engage in the intimate conversation of loving friends, as I have witnessed many times. They use their customary speech, which enables them to express more in a minute than we could over the course of an hour. As noted, their language is universal, common to all tongues, because it uses ideas—the rudiments of all words—as its medium. They discuss things with such acumen and insight, pursuing so many well-constructed, persuasive lines of reasoning that if people knew about it they would be dumbfounded. Spirits link opinion and feeling, which lends animation to their speech.
Sometimes spirits employ representations as well—an appeal to the eye and so to living experience. Take for example a discussion of shame and the question of whether it can exist apart from reverence. People on earth cannot settle the matter without endless argument involving various proofs and examples, and even then the issue remains in doubt. Spirits, on the other hand, take only a minute. They run in order through the various ways in which shame affects us and then the ways in which reverence does, noticing points of agreement and disagreement. These they also observe in visual representations connected to their speech. From the evidence, they instantly arrive at a conclusion, which rises spontaneously out of the harmony thus imposed on conflicting ideas. All other subjects are dealt with in the same way.
Our souls take up this ability immediately after death. Good spirits like nothing better at that time than to teach uninformed newcomers.
The spirits themselves are unaware—unless the Lord inspires them to reflect on it—that they speak such an exalted language among themselves or that they enjoy such an outstanding gift. This way of speaking is natural for them, and by then it is ingrained. Their situation is like that of people who fix their minds on the meaning of a message and not on the words or form of expression: if they do not reflect on it, they sometimes do not even know what language is being used.
from Secrets of Heaven, Volume 2, Section 1641