When i toch my testicles i see there is small third piece of testicles .what is that.is it it normal or.what i need to do.

Get checked: I really can't say without doing an exam. Please see a doc to make certain it's nothing serious such as testicular cancer. Kudos for checking yourself!

See your doctor: You need a testicular exam by your doctor and possibly an testicular ultrasound to rule out any abnormalities. Continue to check your testicles once a month.

Spermatocele: Which is name for cyst of the epididymis or hydrocele of the cord, most likely explanation. Both are benign. Less likely an inguino-scrotal hernia, however, best to see dr and get a scrotal ultrasound which will give the answer. Unlikely to be an extra-testicular tumor. Good luck.