Live and learn.

Experience continually teaches people new things, often through mistakes, surprises, or changing circumstances. The saying acknowledges that learning is not finished and that ordinary life can correct assumptions.

It can also be a resigned but good-humored response after discovering something unexpected. Rather than dwelling on embarrassment or frustration, the speaker treats the discovery as another lesson gained through living.

Use it after a new realization, especially one prompted by an error or unexpected event. It may be said about oneself or another person in a reflective, lightly humorous, or accepting tone, rather than as a severe rebuke. Directed at someone facing serious difficulty, it can sound dismissive.