Multiplication is when you times two different numbers together where its negative or postive(you can multiple pretty much anything together)but combining like terms are number or letters thats the same. For instance, say if i have 4x+7-2x+3, i would combine each term that has something in common with it,like, 4x and 2x because both has X and i will combine 7 and 3 because those two are regular numbers and does not have an X like the others. I Hope That helps!