These are first and last letters of the Greek alphabet. Possible meanings are 1) "the one who began all things and who ends all things" or 2) "the one who has always lived and who always will live." If unclear to readers you may consider using the first and last letters of your alphabet. Alternate translation: "the A and the Z" or "the first and the last" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-merism]])