Sometimes, you may need to tag an item with its color or size. In this case, you can create colors and sizes as variations and assign them to the item. Please follow this guide to create variations.
Click on “Product” and go to “Variation Type”.
Click on “New” to add an variations category if you want.
Select an variation category and click on “Add”.
Enter the variation infomation and click on “Save”.
Then the attribute is set up well.