Aang, A Lot to Learn is a uncommon Legendary Creature — Human Avatar Ally card from Avatar: The Last Airbender Eternal (TLE), collector number 146. Current market price: $0.15 (foil $0.41), TCGplayer market prices via Scryfall.
Aang has vigilance as long as there's a Lesson card in your graveyard. Whenever another creature you control dies, put a +1/+1 counter on Aang.