Understanding typescript syntax for createContext

I am new to typescript.

Can someone please explain the syntax here?

Why are there two groups of signIn, signOut and user and what is the purpose of those two groups?

Does the first group define what is returned and the next group is accepted params?

const AuthContext = React.createContext<{
  signIn(): void
  signOut(): void
  user: UserType | null
}>({
  signIn: () => undefined,
  signOut: () => undefined,
  user: null,
});

>Solution :

This first part righ here:

{
  signIn(): void
  signOut(): void
  user: UserType | null
}

Tells the type of the incoming variable.

This could be replaced by:

type CustomContext = {
  signIn(): void
  signOut(): void
  user: UserType | null
};

const AuthContext = React.createContext<CustomContext>();

The second part is a inline variable. e.g.:

let contextDefaults = {
  signIn: () => undefined,
  signOut: () => undefined,
  user: null,
};

const AuthContext = React.createContext<CustomContext>(contextDefaults);