There is nothing to do in the airport. There is a hotel adjacent to the airport, but I would recommend the Traders (formerly Holiday Inn) on the mainland -- about a five-minute (complimentary) boat ride. They have a roof-top pool and (non-alcoholic) lounge, which is a nice place to see the sunset. The hotel is not cheap, however.

You could wander around the island and get a small taste of local flavor, though there isn't much to see. You could go to a coffee shop, local restaurant, or market. I am not sure if there is a public beach on the island, but you could check.

I wouldn't advocate going only to Male for vacation, but it certainly beats sitting in the airport.