What does a wolf in sheep's clothing mean?

"Wolf in sheep's clothing" is used to describe a person who looks very amiable on the surface, but in fact he has bad intentions, can't be trusted and needs to be careful. Wolf in sheep's clothing is one of Aesop's fables in ancient Greece.

Example:

1. You need to be good shepherds, know your sheep, and the sheep know you, and distinguish wolves in sheep's clothing.

2. When a wolf falls in love with a sheep, he has a wolf in sheep's clothing. I fell in love with you and have a bright future.

3. You say that you are a wolf in sheep's clothing, then I am the lamb kept by the wolf.