"Do your work."
Translation:अपना काम करो।
Ummm.... It is sort of complicated for me to explain. But let me try....
अपना is used to express the belonging of the subject.
Eg आप अपना काम करो। (You do your work)
वो अपना काम करे। (He shall do his work)
आपका would be used if someone else was doing the work of person in front of me.
वो आपका काम करे| (He shall do your work)
To say You do his work. आप उसका काम करो|
I hope this clears things up a bit