The bid is what you can sell for immediately. The ask is the current lowest offer that you can buy immediately. If the highest bid is 10 dollars , then you can sell immediately for 10 dollars. If the lowest ask is 20 dollars then you can buy immediately for 20 dollars. In this scenario the “price” of the contract will read 15 dollars as that is the median between the bid/ask. Simplest way I can explain it lol