This is the 12th most frequent Japanese word.
さ
The Japanese word "さ" is a sentence-ending particle used to express assertion, familiarity, or emphasis.
The particle "さ" is used here as an emphatic or casual speech-ending particle, emphasizing the speaker’s mood.
すごいのさ。
It's amazing.
The word "さ" acts as an interjection to express readiness or to draw attention before an action.
さあ、行こう！
Well, let's go!
The particle "さ" adds a sense of casualness or resignation to the statement, showing the speaker’s tone.