Okay, imagine you have a garden that has pretty flowers or yummy vegetables. You need to give them water so they can grow big and strong. But you can't just pour water straight from a big bottle or bucket because it might be too much water all at once and might hurt your plants.
That's where a watering can comes in! A watering can is like a little bucket with a spout on top and a handle to hold it. You can fill it up with water from your house or a hose and then carefully pour just the right amount of water onto your plants.
Think of it like using a cup to drink your milk instead of just sticking your mouth in the giant milk jug and gushing too much milk all over your face. The watering can helps you water your plants just right so they can grow big and healthy.