STAB + Super effective

STAB is 25% damage boost
Super Effective is 2x Damage
STAB + SE = 2.5x Damage

@Dusk, To be honest, I'm not sure how much Super Effective actually does. I went with what this site said, which was 2x Damage.

The rest of the answers are not right.

STAB (In go) is 1.25 and S.effective is 1.25

Combined it should be 1.5

I think Naen is right as to the numbers of the bonuses, but he's seemingly assuming a) that they're added (when other things like dual weaknesses aren't combined in any combination), and b) that they're additively added (i.e., 1.0+[.25+.25]) as opposed to multiplicatively multiplied like they are in the main games, which would result in 1.5625 total damage multiplier. Certain games like Injustice Mobile do have all damage added additively, and in this game everything is scaled down, so it's possible they went that route, but the difference between all of 1.25, 1.5 and 1.5625 is relatively small enough that only coding will reveal all.