Solenoids are made of a big coil of copper wire with an armature in the middle, basically electromagnets.
This has nice mounting tabs, its a great all-purpose solenoid.
The solenoid is able to pull or push This solenoid in particular is fairly small, with a 30mm long body and a 'captive' armature with a return spring. This means that when activated with up to 24VDC, the solenoid moves and then the voltage is removed it springs back to the original position.
To drive a solenoid you will a power transistor and a diode, check the diagram below for how to wire it to an Arduino.
A fairly good power supply to drive a solenoid, as a lot of current will rush into the solenoid to charge up the electro-magnet, about 100mA, so don't try to power it with a 9V battery!