Yes. Now, to be technical and extremely literal, you can’t redeem them for cash in the sense that you’ll actually see the green stuff. You won’t redeem the points and then receive an envelope full dollar bills.
But you will see a credit on your American Express statement, which means that your next bill should be lower than it would been otherwise. You’ll be getting cash back – it’s just going to appear on your statement.
That said, your Amex points are worth more when you use them for travel, and so you do want to consider that. But if you’re not going anywhere any time soon, lowering your credit card bill means more cash will be left in your bank account.