There are various shops that will help on your adventure. Note that not all shops appear in all towns.

Inn	Spend the night here to restore the HP and FP of all party members.
Tool Shops	Purchase weapons, armour, items and accessories here. You can also sell any items you don’t need.
Treasure Shop	Purchase rare items here.
Drink Shop	Purchase drinks that restore HP and FP.
Mushroom Shop	Exchange mushrooms for items.
Beetles Are Us	Exchange beetles for coins or Frog Coins.