What does a lighting engineer do?

they design the lighting set up and they look at the scene they do this using genre stereotypes and semiology.

They maintain the lights they have to able to take them off the rig and repair them also to make sure they are all working before the scene is ready to shoot.

They set up the lights to the design agreed by the director and they have to be able to modify them if needed.

How to become a lighting engineer?

Get work experience!, having work experience is vital because the people who do lighting know pretty much everything there is you need to know. However, you should still go to university as it does give you possible connections and it proves your ability to get  a higher level of education.

you can also do an internship, apprenticeship, or became freelance you will probably need the experience to become a freelance however you will probably be hired more than going to an apprenticeship or an internship.