This is the 2766th most frequent German word.
letzter
"Letzter" means "last" or "final" in English.
In this sentence, 'letzte' is used as an adjective to denote the final person in the sequence who performed the action.
Er war der letzte, der den Raum verließ.
He was the last to leave the room.
Here, 'letzten' (inflected form of 'letzter') describes the previous year in a temporal context.
Im letzten Jahr habe ich viele neue Dinge gelernt.
Last year, I learned many new things.
In this case, 'letzten Worte' refers to the final words of a book, emphasizing the concluding nature of those words.