Okay kiddo, so grapevines are like plants that grow grapes. They are kind of like big and twisty, like big long stems that go up and down and all around like spaghetti. They grow these special things called grapes that you can eat or use to make juice or wine.
The grapevines need sunshine and water to grow properly, just like you need food and water to grow strong and healthy. They also need something to cling onto, kind of like how you hold onto your mom or dad when you are learning to walk. That's why they usually grow on things like trellises or fences or other support structures so they can climb up and grow strong.
Grapevines also have different parts, like leaves and roots and flowers. The leaves help make food for the grapevine and the flowers eventually turn into grapes. The roots help the grapevine stay strong and healthy by getting water and nutrients from the soil.
So that's basically what a grapevine is - a plant that grows grapes and needs sunshine, water, and something to climb on to grow big and strong.