infernape only has one ability so that doesnt apply to him but basically the ability 1/2 determines which of the two (if it has two) abilities the pokemon can have, for example, rhyperior can have the abilities lightning rod or solid rock, that means that if it has ability one it has lightning rod and ability 2 is solid rock, if you look on smogon they show the abilities in that order (the 1 ability first, the 2 ability second)
im rushed for time right now so this may not be perfectly clear to you
EDIT: here is a picture to show you what i mean