We can use division to know how many groups with a certain number of parts form a whole. We this happens, we are interested in know the number of groups more than the number in each group.
For example, we know that in a school we have 300 students and each classrooms has 30 students. How many classrooms there's in this school? In that case, we know that there's 300/30 = 10 classrooms. So, we divide here to know the numer of groups of students (classrooms).
But, sometimes, we also can divide to know the number in each groups. For example, if we were told only that in that school we had 300 students and 10 classroom, to know the number of students in each classroom (group), we also would need to divide 300/10 = 30 students per classroom.
Therefore, we can use division to find the number of groups as much as we can use it to find the number in each group.