During winter you might wear knitwear and heavy wool coats, and in summer you wear more shorts and dresses.
A capsule wardrobe in its original sense, is a “collection” (or capsule as the name refers to) with clothes and shoes, that you can adjust from season to season and that you LOVE to wear. During winter you might wear knitwear and heavy wool coats, and in summer you wear more shorts and dresses. The essence is to store away the items that don’t fit the season you’re in, so you only ever have items you are actually able to wear in your wardrobe. Then when the seasons change, you get to “shop” your good old faves. Clever, right?