120 Hz means a vibration 120 cycles per second.
These are called harmonics. If you have a signal at 60 Hz, then there may be harmonic signals (typically of lesser intensity) at 2x, 3x, 4x, etc. of the base frequency. So these would be at 120 Hz, 180 Hz, 240 Hz, etc.
As clock motors are synchronous in design for a particular frequency, the 60 Hz clock will run slower on 50 Hz.
If you mean the USA, there they use 120 volts / 60 Hz.
A 250 ATV can go from 80 to 120 kmh
120 V @ 60 Hz
240 V @ 50 Hz (US and Canada are 120 V @ 60 Hz)
120 volts 60 hz
1/120 seconds!
120 volts 60 Hz AC
120 volts 60 Hz AC
An ATV driver? You mean an ATV racer.