There are two important aspects to this verse.
First, there is the aspect of it that is saying that sex within a marriage is a good thing. Paul is telling the Corinthians that there is nothing evil about sex within marriage. It is something that should be done willingly and without guilt.
Second, there is the aspect of the verse that has to do with expectations about men and women. Today (though perhaps not as much as was true a few decades ago) we often have the idea that sex is something that men want and women simply put up with. But Paul is not portraying it in this way. He says that both the wife and the husband should fulfill their sexual duty to the other. In this way, Paul seems to be saying that both partners will want sex and both partners must willingly give their bodies to the other.