To bring back means to return with something or someone, or to cause something from the past to exist again.

When your parents ask you to bring back milk from the store, they want you to return home carrying it. When a library book is due, you need to bring it back before the deadline. The phrase suggests a return journey: you go somewhere, get something, and come back with it.

The phrase also means to revive or restore something that had disappeared or been forgotten. A school might bring back an old tradition like field day after years without it. A restaurant could bring back a popular menu item. Scientists dream of using DNA to bring back extinct species like woolly mammoths, though that remains science fiction for now.

Sometimes memories can bring back feelings from the past. A familiar song might bring back memories of summer camp, making you feel the same excitement you felt years ago. In this sense, the phrase describes how certain experiences can transport us emotionally to another time, even though we haven't physically traveled anywhere.