Signing Tip: Make sure that the moving hand is your dominant hand, not your passive hand.
Example: "Can you spell that again?"
Grammar Tip: This is a yes/no question which means you should raise your eyebrows for the whole question. People might be tempted to sign CAN for this question but it is not necessary as the CAN YOU aspect is shown in the eyebrows basically. This is more of a request as opposed to asking whether someone is able to do something.