With anything scientific, people generally talk about giga (G) being 1x10^9. That's an American billion.
A French/British billion (1x10^12) is tera (T) in SI prefixes.
So, since we take 1 eV to be 1.60x10^-19 J (to 3 sig. figs.), 1TeV (units are case sensitive) is:
1.6x10^-19 x 1x10^12 =
1.60x10^-7 J, or, with SI prefixes, 160 nJ (nanojoules, 10^-9)
(Strictly speaking, the Joule isn't the SI standard. In base units, the Joule is:
because W (energy) = F (force, in newtons, which is also not an SI base unit) * d (distance, in metres, which is a base unit)
F (force, N) = m (mass, in kilogrammes, a base unit) * acceleration (in ms^-2, which is expressed in base units)
So W = mad or, in units, kg * ms^-2 * m. Which simplifies to give the unit above.
But everyone just uses J.)
You may or may not have known all that, but other people may benefit. Disclaimer: I don't claim to be perfectly right, but this is my understanding of the SI units, and it's served me well so far.