One of several different elemental types! Seems every Pokémon is categorized into at least one of them, though I imagine you'll mostly encounter Normal types for a while.

[That's what he's gathered from the Pokédex and map functions, at any rate. As he never started in New Bark, this is all guesswork at the moment.]

I'm glad you managed to retrieve it! It's important that you pace yourself, since I believe it's a few days to the next town. Do you by any chance have a traveling companion?