Two types have compatible type if their types are the same: confused

Question

C2x (N2596), 6.2.7 Compatible type and composite type, 1:

Two types have compatible type if their types are the same.

The grammar of that sentence is confusing.

For example:

• How type can have a type? Or what does "their types" mean?
• What does it mean "compatible type"? Any examples?

Please clarify who knows the topic well.

UPD. Here is the rephrased sentence:

Two types are compatible if they are the same.

Answer 1

The sentence means if the type X and the type Y are the same type, then X is compatible with Y (and vice-versa, of course).

In mathematical terms, it means compatibility is reflexive (any type is compatible with itself).