Addition is getting more of things. Imagine you have one apple, and your friend gives you one apple. Now you have more than one apple! That's addition!
Now let's try a more difficult problem. Imagine you have two apples, and your friend gives you two more apples. How many do you have now? No, no, Mr. Poor, you don't have five! Does anyone else have an answer?
No? Then let's try again without liberal deceit: Imagine you have one apple, and you steal one apple from your hypothetical friend. Now you have more than one apple! That's a profit!