Pumpkin pie is a food item that can be eaten by the player. To eat pumpkin pie, press and hold use while it is selected in the hotbar. Eating one restores 8 hunger and 4.8 saturation.
Apprentice-level farmer villagers have a 50% (Bedrock Edition only) or 2/3 (Java Edition only) chance to sell 4 pumpkin pies for an emerald as part of their trades. In Java Edition, farmer villagers throw pumpkin pies at players under the Hero of the Village effect.
Read more about pumpkin pie on https://minecraft.fandom.com/wiki/Pumpkin_Pie