Does anyone know how your pet can use them?

Alchemy points for your pet are gained when you read books to them (or otherwise raise their intelligence). They allow you to use special scrolls in battles.

The Complete Scroll List

That forum thread has a list of the scrolls with what they do and how many alchemy points it costs to be able to use them. The points for the scrolls add up, so if you want to use one that costs 8 AP and another that costs 10 AP, your pet will need at least 18 total alchemy points to use them both.

Sounds good but what does this mean?

Roscoe_Goat's Learned Scrolls No Spells Learned! 0/29 alchemy points used

It's not really as relevant since you can make scroll sets in the Coli now instead of teaching them directly to a pet. But if you do teach your scroll to a pet instead, the number of AP used would go up. If you use a scroll set instead, you just need to make sure your pet has at least that number of AP (so if you have 30 points worth of scrolls in your set, you need at least 30 AP to use it)

Sounds good, how do you teach your pet a scroll?

Oh, sorry I think you've gotta use the scroll library now :x Sorry, I really thought it was still available to just teach the scroll to your pet, my bad