Minecraft wiki entry for Shelters, associated text: Armor shop: sells armor for protection.
Tool shop: sells tools for breaking things faster.
Potion shop: sells potions for health.
Food shop: sells food for hunger. Note: Rotten flesh, poisonous potatoes, raw chicken, pufferfish and spider eyes have food poisoning, so do not sell those in a food shop.
Weapon shop: sells weapons for killing animals or monsters.