A gamepad (or “controller”, etc.) a handheld input device for games, typical of home game consoles.
The default gamepad on a modern system, has both a “d-pad” and at least one “analog stick” for directional input, as well as several buttons.
For fighting games, this is mostly considered less desirable as an input device than an arcade-style “stick”, but some players prefer it, and some players can’t afford any other equipment.