Aorist usually expresses past tense. For example from SN 44.10:
bhagavā tuṇhī ahosi
The Buddha was silent.
It is a complex verbal form, and is expressed in many, not very regular, ways in the Pali.
In some cases it doesn’t mean past tense, especially when used with mā, “do not!” In such cases it expresses a prohibition. From SN 6.10:
mā hevaṃ, kokālika, avaca
Kokālika, do not say that!
I have no idea how it relates to aorist in other languages. Always remember that grammatical categories are mere summaries of usage. When we use the same word “aorist” in different languages, all we are saying is that the usages in those two languages bear some similarities, not that they are somehow the “same thing”.