If you give someone a piece of your mind, you tell them very clearly that you think they have behaved badly. How very thoughtless. I'll give him a piece of my mind
You can use piece of with many uncount nouns to refer to an individual thing of a particular kind. For example, you can refer to some advice as a piece of advice. When I produced this piece of work, my lecturers were very critical an interesting piece of information. a sturdy piece of furniture
You use to pieces in expressions such as `smash to pieces', and mainly in British English `fall to pieces' or `take something to pieces', when you are describing how something is broken or comes apart so that it is in separate pieces. If the shell had hit the boat, it would have blown it to pieces Do you wear your old clothes until they fall to pieces?
eat intermittently; take small bites of; "He pieced at the sandwich all morning"; "She never eats a full meal--she just nibbles"
a portion of a natural object; "they analyzed the river into three parts"; "he needed a piece of granite"