Desert can be used as a noun (= substantiv), verb, or adjective. As a noun, desert refers to a large, dry area with few plants (like Sahara). As a verb, it means to leave someone or something behind (“to abandon”). As an adjective, it describes an abandoned place.
Examples
The Sahara is a desert (= noun) located on the African continent.
A soldier who deserts (= verb) the army can get into trouble.
A desert (= adjective) island.
Swedish
öken, öde
överge, desertera
Dessert is a noun that means the sweet thing you sometimes eat after dinner, like fruit, ice cream, or cake.
Examples
The restaurant serves chocolate cake and apple pie for dessert.
My kids always want dessert, but we cannot afford it.
Tiramisu is a traditional Italian dessert.
Swedish
efterrätt, dessert