You say you understand, but your actions don't reflect it.
You say you understand, but your actions don't reflect it.
Your words and actions don't match.
You keep saying you understand, but you keep making the same mistakes.
You need to take responsibility for your words and follow through with action.
「言葉では分かったと言うが行動が伴ってない」は英語で、
your actions don't reflect your words
your words and actions don't match
という表現がとてもよく使われます。