When the foreskin is too tight, it's difficult to pull it back over the glans of the penis. For a boy less than 5 years old, it's naturally difficult to do this, and it shouldn't be forced because of the a risk of creating tiny lesions. Every young boy should be taught to pull the foreskin back when he goes to the toilet to clean the area.
The surgeon makes an incision into the foreskin which alllows him to treat the foreskin and give it a larger shape.
The days after the operation will not be pleasant. Once healed, the enlarged foreskin can easily be pulled back over the glans and sex will be pain-free.