Myomectomy is surgical removal of uterine fibroids. Its goal is to repair the uterus and bring it back to its usual functioning. It is the only surgical procedure for uterine fibroids that can preserve the possibility of getting pregnant after it.
The main practical goal here is to stop heavy bleeding and pressure on the internal organs from the (possibly large) fibroids. The disadvantage is that fibroids can happen again. Fibroids that are cut out cannot come back, but if nothing else changes in the life of the patient, fibroids that were not operated upon may grow larger, or new ones can form. If there were one or two large fibroids and they were taken out, the risk of other such fibroids growing again is low. If there were a large number of small fibroids and some of them were not taken out during myomectomy, they can just continue growing as if no surgery ever happened.