An exclamation praising someone's action or achievement: "Well done!" or "Good job!" — used informally.
テストで満点だって？よくやった！
You got a perfect score on the test? Well done!
よくやった、チーム全員の努力の結果だよ。
Good job — it's the result of the whole team's effort.
子どもがピアノを弾き終えたとき、母が『よくやった』と微笑んだ。
When the child finished playing the piano, his mother smiled and said, "Well done."