One's life: the span of existence and the experiences and path a person goes through.
人生は一度きりだから、自分のやりたいことをやりなさい。
You only live once, so do what you want to do.
彼は人生の意味についてよく考える人だ。
He is someone who often thinks about the meaning of life.
失敗も人生の大切な経験だ。
Failures are also important experiences in life.