What figurative language is this? > lee always get 100% on his test ; he knows absolutely everything there is to know about math

The figurative language used in this expression is IDIOM, commonly used to refer to a person who knows very much about everything. In this case it refers to a very good student that gets the better grades in his exams. Anyway, idioms are expressions that usually cannot be explained word by word, they have to be taken as a whole.

The sentence uses figurative language called hyperbole.

Hyperbole is a figurative language technique that uses exaggeration to create a strong. Of course, Lee doesn't know everything about math, but the use of  hyperbole expresses that Lee knows a great deal of math.  

i am for my child

in june, we will have been married for eighteen months. (i am assuming this is what you want? the sentence, as you have presented it, is grammatically incorrect--   you want it corrected, yes? )