Recap kit, a preselected group of capacitors or caps for short. Its not necessary to buy a selected kit, you can just buy capacitors you need individually.
Recapping, replacing all the capacitors.
Recapping a monitor, replacing the capacitors with new working capacitors.
Capacitors are used to filter, smooth out or store electricity for a circuit.
Every Capacitor have a capacitance or how much that part can store up electricity to filter and smooth out the flow of electricity in a circuit.
Capacitors can also be used to generate greater voltage than what a device is supplies like in a taser or in this case a monitor. As CRT Monitors are High voltage devices.
Most capacitors contain a electrolytic fluid, as they get old and fail they can leak. This fluid is how the capacitor holds its capacitance. Capacitors can loose its capacitance if they start to wear down with age, they can bulge and even burst.
Similar to batteries Capacitors when they leak, the fluid is highly corrosive, the corrosive fluid can damage near by circuits.