Chatterbox
A chatterbox is someone who talks a lot, often about things that aren't very important, and doesn't let others speak much.

Synonyms:
1- chatty 2- talkative

Examples:
1- At the family dinner, Grandpa became a chatterbox, sharing stories from his younger days.
2- Alice is such a chatterbox; she talks non-stop about her day, and it's hard to get a word in.