You need to add variations if your products have variants, Like size, colors etc. In Odoo you can manage the product at the template level (for all variations) and at the variant level (specific attributes).
As an example, a company selling t-shirts may have the following product:
B&C T-shirt
Sizes: S, M, L, XL, XXL
Colors: Blue, Red, White, Black
In this example, B&C T-Shirt is called the product template and B&C T-Shirt, S, Blue is a variant. Sizes and color are attributes.
The above example has a total of 20 different products (5 sizes x 4 colors). Each one of these products has its own inventory, sales, etc.
To activate the product variants in the settings. Go to the Sales app. In the menu Configuration ‣ Settings, locate the Products Variants line, and tick the option Products can have several attributes, then click on Apply.
Once you have activated the variant option, you can add variants to your products. To do so, go to the Sales module, Sales ‣ Products. It is also accessible from the Purchase and inventory modules.
Now, click on the product you wish to add variants to.
In the product page, a new tab called Variants has appeared. The number in purple written on top is the number of variants this product currently has. To add new variants, click on the tile. In the new window, click on Create.
In Attributes, click on the rolldown menu and select the type of variance you wish to add. If the variant does not yet exist, you can create it on the fly by clicking on Create and edit…
In the Attributes window, the Value field is the description of the attribute such as Green, Plastic, or 32GB. The Attribute field is the type of variants such as Color, Material or Memory.
You can add a cost for the variant on the fly by adding it in the Attribute Price Extra field or choose to modify it later. Click on Save.
You can also add a different barcode and internal reference to the variant.
When you have entered all the specifications of the variant, click on Save.