The Falcon 9 deployed the X-37B Orbital Test Vehicle, as the payload is officially called, and then its first stage booster returned to Earth for a planned recovery at Cape Canaveral Air Force base via SpaceX’s LZ-1 landing pad. The goal was to get the launch up before the arrival of Hurricane Irma, and they succeeded. While the specifics of the X-37B’s mission aren’t available to the public, it will be “conducting experiments” post-launch. Its last mission saw it orbit Earth for two years before returning via a landing in May. The X-37B, built by Boeing, is an uncrewed vehicle, but resembles the Space Shuttle on a smaller scale. It’s also designed to land like the Shuttle, using a landing strip like you’d use for an airliner.
Successful SpaceX launches are now becoming commonplace. This is what SpaceX has been aiming for for years.