My baby is 3 months old and doctor tell that he has umbilical hernia. so i want to ask that, can this heal itself?

Kids seldom need rpr: Loose belly muscles help a developing fetus by allowing easy blood flow thru the umbilical cord & into babies body. After birth, that loosness may allow a transient umbilical hernia that will usually disappear when the belly muscles tighten, starting after baby learns to sit.By 2yo most uh have receded. I find girls more likely to need repair than boys ? I rarely refer for repair <2y.

Yes: Umbilical hernias are common in newborns and usually close by age 2. Nothing to worry about unless it seems to be painful for him, or he has a hard lump at the umbilicus.