What is the use and meaning of the underlined portion of the sentence below?

My little sister Annie is an angel who always follows the rules and tries to do what she thinks is right.

1 answer

"My little sister Annie is an angel" - This phrase is an idiom used to convey that Annie is a very good and well-behaved person. It implies that she is kind, helpful, obedient, and generally delightful to be around.