A type is a collection of possible values. An integer can have values 0, 1, 2, 3, etc.; a boolean can have values true and false. We can imagine any type we like: for example, a HighFive type that allows the values "hi" or 5, but nothing else. It's not a string and it's not an integer; it's its own, separate type.
Statically typed languages constrain variables' types: the programming language might know, for example, that x is an Integer.
In that case, the programmer isn't allowed to say x = true; that would be an invalid program.
The compiler will refuse to compile it, so we can't even run it.