The height of this mountain is three thousand meters.
彼女は仕事の大変さをよく知っている。
She knows well how hard the work is.
assertive sentence-ending particle
Casual sentence-final particle that gives a statement an assured, matter-of-fact, or lightly emphatic tone. It as mainly masculine.
心配するな。大丈夫さ。
Don't worry. It'll be fine.
そんなこと、僕にだってできるさ。
I can do that too, you know.
I measured the weight of this box.
I don't know about that, that's just how it is.
Come on, let's go.