How is GraphQL better than REST?

Question

Due to the fact that someone hates me and reduces this question, I want to make sure that I understand how GraphQL works. Here's my understanding of one of the ways GraphQL is superior to the RESTful API. Let's say you have a model user:

{
  user: {
    firstName: "John",
    lasName: "Smith",
    username: "jsmith",
    email: "[e-mail]",
    gender: "M",
    password: "password"
  }
}

Then you call the API of getthis user information for your application’s profile page. Suppose you only need a user firstName(perhaps to display a welcome message).

axios.get(get_user_info_url).then(res => {
  const firstName = res.data.user.firstName
})

, , , res , , (, username email). , . firstName . , user ( ) , , , .

, , res.data.user.firstName. GraphQL firstName, . , GraphQL (overfetching).  , , (, firstName). , , / .

GraphQL?