Any product is more attractive to a customer when it has not one image. Especially when you search for some clothes, bag, shoes etc.
Also when you choose among options in some product you prefer to see an image of the desired colour option. And the last thing when you choose clothes is the most popular colours and sizes. For example, some shoe sizes can be sold quickly. The same situation with the clothes colours. So, a client wants to see on a site what sizes and what colours are left and which ones are is already absent.
As many popular cms eCommerce system WordPress with Woocommerce plugin provides such useful functionality by default.
We recommend always to update WordPress itself and WooCommerce plugin to the latest version. Some new options can be added or/and bug fixes in it. On the moment of current article writing and publishing the current WooCommerce version is 3.4.5.
So, follow steps to create and add the Sizes and Colors Attributes:
1) Create an attribute in admin
Create the Color Attribute firstly. Go in admin left panel: Products -> Attributes -> add new attribute.