MY DENTIST SAYS HE'S GONNA CUT OFF PART OF MY GUMS?

he says my gums look really swollen in the front part, (i have braces, and are closing a gap in the middle) and they are, but it doesn't bother me, but now im scared beouse the says their gonna remove the extra tissue closing up together. has anyone eles ever had this? can you tell me what they will do? and if it's painfull? thanxz♥