1 electron volt (1 eV) is the energy an electron receives if it is accelerated by a voltage of 1 Volt.

In a computer screen the electrons are accelerated by a voltage of around 15000 Volt, also written as 15 kV. The electrons then receive the energy 15 keV (kilo electron volt).

In the LEP accelerator at CERN, the electrons and positrons can be accelerated with a voltage of totally around 100 billion volt = 100 GeV (100 giga electron volt).

1 eV
1 000 eV = 1 keV
1 000 000 eV = 1 MeV
1 000 000 000 eV = 1 GeV
1 000 000 000 000 eV = 1 TeV

The acceleration steps in a linear particle accelerator. (Source CERN)