Student or Learner
"the business modules cross over a lot with the Economics ones I did last year, which whilst hard are very rewarding!"'
In this sentence, what does "whilst hard" mean exactly? I guess it probably mean something like "although it's hard" Am I right?
You're nearly right. It means 'although they are hard' (as modules is plural).
Tip for a better title (and a shorter one): Whilst hard.