"They are a lot taller than us."
Translation:Ils sont beaucoup plus grands que nous.
Why does 'plus' have to be in the sentence. A lot taller is beaucoup grands, is it not. Someone should please explain because I do not understand
beaucoup grand(s) = a lot big / tall. beaucoup plus grand(s) = a lot taller / bigger.
Plus grand = taller / bigger.
Plus petit = smaller
Just a remark: beaucoup grand(s) is not possible in French (I'm not sure about a lot big in English). beaucoup can only modify verb and adverbs, so you can say beaucoup plus grand because there is plus.
Think of "plus" as the "er" that makes "tall" become "taller". Example: jeune=young; plus jeune = younger.