The word pump has several meanings:

1. A machine that moves liquids or gases from one place to another. A bicycle pump pushes air into tires. A water pump might lift water from a well deep underground, or a heart pump in a hospital might help a patient's blood flow properly. Gas stations use pumps to move fuel from underground tanks into cars. The pump does work that would be difficult or impossible by hand, creating pressure that forces the liquid or gas to move where you want it to go.
2. To move something using a pump, or to move in a way that resembles a pump's action. You pump air into a basketball before a game. You might pump your fist in celebration after scoring a goal. A cyclist pumps the pedals hard going uphill, pushing down with force on each stroke.
3. To question someone persistently to get information. If your friend pumps you for details about a surprise party, they're asking lots of questions trying to extract the secret. This usage suggests effort and persistence, like working a pump handle.

The word can also appear in expressions like pumped up, meaning excited and energized, as when a team gets pumped up before a big game.