If you have products that have multiple colors and sizes, then you can add variants to those products. Each combination of color and size for a product is a variant for that product. A product can have multiple sizes, or multiple colors or a combination of both.
For example, suppose that you sell t-shirts with multiple sizes and colors. The size has three values: small, medium, and large. The color has two values: blue and green. One variant from these options is a small, blue t-shirt.
You can add variants when you are creating a product, and you can add or edit variants for an existing product at any time.
To add variants while you're adding a product, go to the Add product page, click Color & Sizes tab.
This option allows you to specify different prices and stock for your product variants.