Well kiddo, have you ever heard someone talk in a very high-pitched, cute and soft voice like a baby? Sometimes people use that voice to sound more attractive or to get what they want. It's called a sexy baby voice, but it can also be called a baby talk, a babble or a coo.
But you know what? Even though some people think it sounds nice, it's not a good idea to use the sexy baby voice all the time. It can be annoying and it's not how we normally talk as grown-ups. Plus, it's important to always use our real voice and speak confidently!