Void is considered a data type (for organizational purposes), but it is basically a keyword to use as a placeholder where you would put a data type, to represent “no data”.
Hence, you can declare a routine which does not return a value as:
void MyRoutine();
But, you cannot declare a variable like this:
void bad_variable;
However, when used as a pointer, then it has a different meaning:
void* vague_pointer;
This declares a pointer, but without specifying which data type it is pointing to.