The array variable a when used alone, it means the memory address (i.e. pointer) of the start of the array.
It is interpreted to be a pointer to the first element of the array, and hence it is an int pointer.
*a means dereferencing the pointer, to get the value of the int at the memory address specified by a.
So, *a is just the value of the first element of the array a. i.e. a[0]
So *a + 1 is the same as a[0] + 1