I have a question regarding power electronics. What is the meaning of 'line to line voltage' what does it tell us and how can this be calculated. Say I have a three phase system how would one find the line to line voltage for this system?
A three-phase system has one neutral wire and three phase wires.
The line-to-line voltage is the voltage between any two of the three phase wires in your three-phase system. It can be measured via a voltmeter in VAC mode with leads clipped to any two of the three phase wires.
If you are concerned with converting between line-to-line and line-to-neutral voltage, check out this source.
For more information on three-phase power (and for a good laugh), check out this Electroboom video.