Duration is the length of time the time laps operation runs for.
Frequency is how often the photo is taken.
For example you could set it to take photos every
5, 10, 30 or 60 seconds (frequency)
And to continue doing that for
5, 10, 15, 20, 30, 60 or unlimited minutes (duration)
Light frequency has to do with the refresh rate of the monitor you are playing back on.
In the USA our TVs use 60Hz refresh rates and combinations of it (60, 120, 240Hz) so don’t change it to 50Hz.
In Europe use 50Hz.