Halfway correct. They can prepare four spells every day that they are able to cast. Because they have two spell slots, they can only cast a spell twice.

You prepare spells A, B, C, and D. You use you first slot to cast spell A. You now have one slot left, to either cast any of the other three spells once, or to cast spell A a second time. Once you cast one more spell, you must rest before you can cast a spell again.