Character needs letter addressed to him read out loud by someone else
A character has just received a letter informing him of some important plot point. But the audience needs to be informed too, and they can't just read over his shoulder. So the letter gets read out loud by the messenger who brought it or someone else already on the scene. There may be a Hand Wave as to why the addressee can't just read the letter himself. This is mostly a theatrical trope. Visual media usually avert it by showing a close-up of the letter, unless they trust the audience to hear lines better than read text. Compare Voiceover Letter.