It means that within the state of NV, you can't place a bet over a desktop or mobile site. You must have a Nevada sportsbook application, and then you'll be all set to start placing bets. Fortunately, most of the US top sports betting sites provide betting app for their users.
Just don't look for either business in Nevada. As with FanDuel and DraftKings, Fanatics and ESPN Bet will not be available anywhere in the Silver State.