Sometimes I see random people saying stuff like "Iso a gen1 wolf" or "how much for this low gen wolf?" What exactly does this mean? is it about the wolf IDs or something like that?

The 'gen' is just the number where they fall in their family line.

A gen2 wolf would be the pup of two wolves with no parents, ie - two gen1s (Either wild wolves or Progen wolves or a mix of the two). A gen3 would be the pup of two gen2s or a gen1 and a gen2 as the pup will go directly after the parent with the highest generation. A gen4 would be a pup of two gen3s or a gen1-2 and a gen3.

If that makes sense anyways. I can try and word it in a better way or get physical examples if needed '^^.

Some are more valuable than others! The less numbers they have the more they're worth, a majority of them are sold for moonstones. I believe 4 digits, especially Wild wolf ones with no pups go for quite a bit and are about the lowest number you can get right now. Low 5 digits are going for about 300 moonstones and 4 digits usually around 1000 - 1500 at lowest from what I've seen. ^^