Sometimes clutter begins to build in creators' tabs of Accepted, Pending, and Delivered tabs...the Archived status means you don't need to see those offers and videos any more. They're still accessible if you need them, under your account settings. Click your icon in the upper right, and you'll see the Archived offer option there.
We moved Archived offers in January 2019 to make room for the new "Offered" tab, the inventory of offers you've been sent individually by publishers. These do not count against your quota.