Here’s the long version:
Galander has it almost right. The attributes are Health, Power, and Speed. Balance is when these are mixed.
Some pets come in only one breed. Anubisath Idol comes only in H/H. Unborn Val’kyr comes in B/B and H/H.
Get the addon Battle Pet Breed ID https://www.curseforge.com/wow/addons/battle_pet_breedid to show breeds.
In general, you will probably find the best breed(s) for pets from this survey:
but if you are looking for specific breeds for the strats to beat the rares in Naz, then go by whatever breeds they use.
The Valk is common enough now. You will find a H/H soon enough. 