Equal groups means that different items will be divided in groups with the same number of items in it.
Example: we have 3 bananas and 5 apples. Finding the smallest common multiple of the two integers 3 and 5, the least common multiple (LCM) will give us the number of items that every group should have.
The LCM is 15.
We will have 15/3=5 groups of bananas with 3 bananas in each and 15/5=3 groups of apples with 5 apples in each.