This is the 6892nd most frequent Korean word.
자
"자" (ja) can mean "ruler" (measuring tool), "chair," "self," or be a casual way to say "let's" depending on context.
The word '자' is used as a suggestion or invitation to perform an action ('앉자' means 'let's sit').
손님이 오셨으니 자리에 앉자.
Since the guests have arrived, let's take a seat.
The word '자' in this sentence signifies a suggestion for a collective action ('나가자' implies 'let's go out').
이제 나가자!
Now, let's go out!
The word '자' here is used as an interjection, similar to saying 'well' or 'alright' to prompt an action or decision.