Questions about example sentences with, and the definition and usage of "Yapper"

A: 'Yapper' refers to someone who talks too much, or the mouth of such a person.
It comes from the verb 'yap', which is a very informal way to say 'talk', and it's usually used when someone is talking too much.

A: Either she has a big mouth (literally), or she talks a lot.

A: “She’s got a yapper.” = 그녀는 많이 말하고

도움이 됐으면 좋겠어요~

A: Yapper is a (very) slang noun to describe a talkative person. It also implies that what they talk about is unimportant or off-topic. Whereas talkative is a formal/proper adjective for someone who talks a lot.