CANDIDATE LINE

If you refer to row 5, you will see that the only cells which contain an 8 are the two highlighted cells. We don't know which one will contain the 8, but one of them certainly will. Therefore an 8 cannot appear elsewhere in the center right 3x3 sub-square which means that the 8 can be removed from C8-R4. Not a great leap forward, but every little bit helps.

Candidate Lines can be quite hard to spot, even when pointed out by a hint, but don't despair. With a bit of practice you will become quite proficient at it.