IPA: /əˈsɔːrtmənt/
KK: /əˈsɔrtmənt/
A group of different types of things or people that are put together.
The store has a large assortment of fruits and vegetables.
Assortment is formed from "assort" (from Old French *assortir*, meaning to arrange or set in order) and "-ment" (a suffix used to form nouns indicating an action or resulting state). The word "assortment" refers to the state of being arranged or a collection of different items.
Think of 'arranging' things ('assort') into a collection or group, which is what an assortment means.