How many extra spells per day do I get with a Wisdom mod of 2?
One extra level 1 spell and, when you are high enough level to able to cast it, one extra level 2 spell.
You can find the table here.
So a spellcasting stat of 20 (modifier +5) would give you 2 bonus spells (or spell slots for prepared casters) per day. If you're high enough level to cast them, you get one extra spell/spell slot for 2nd, 3rd, 4th and 5th level spells.
Ok, thanks.