I work out 4-5 times a week.my biceps become very hard after little work out.people say it's a problem.I massage my biceps after evry set of work out.my biceps are also not pumping. I am under weight.plzzzzzz help me

Why should it be a problem? If your muscles do what you want them to, then it's not a problem if they feel hard or soft. Stretch well AFTER lifting.

Make sure you are are doing lots of squats, deadlifts, rows, bench press etc in the gym, not just arm exercises.