Si jai 2 pomme +5 bannane
sa donne combien

It looks like we are given a simple math question in French which we need to solve.  Before we can begin to answer the question, we can first try to translate the sentence we are given piece by piece.

There appear to be some spelling errors in the sentence: J'ai needs an apostrophe because it is the contracted form of je ai; there are multiple pommes and bananes (2 and 5, respectively), so they must both be in plural form; and lastly, the word, although phonetically is sa, is spelled ça.

Here is the corrected sentence:

Si j'ai 2 pommes + 5 bananes, ça donne combien ?

To revisit some vocabulary, une pomme is an apple, and une banane is a banana.  

J'ai is the conjugation of the verb avoir ("to have") for the subject je.

Vocabulary is something you will have to memorise, but some more pertinent vocab words follow:

Note: Recall that adjectives come after nouns in French, whereas in English, they come before nouns.  You will need to change the order when translating.

Given the above, we can translate the sentence:

If I have 2 apples + 5 bananas, how much does it give?

or

If I have 2 apples + 5 bananas, how much do I have?

Well, 5 plus 2 is 7, so the answer is 7.

7 or sept au total

mangez, buvez because it's giving an order