It's likely a benign hydrocele, spermatocele, or varicocele. Lots of men get them and they typically don't cause complications, but it's best to confirm with a doctor anyway.
Hi,
Did you have any scrotum injuiry in the recent times? Nevertheless, such cysts are quite common, and you need not have to worry much, but should always be checked by a doctor. Please consult a urologist for proper diagnosis.
Solace