Umrah is a very important worship which can be performed during any month in the year, not like Hajj which has its special time in the month of Thil Hijjah. Umrah Mofradah includes Tawaaf around the Ka'ba and Sa'ee between Safa and Marwah which was performed by all the Prophets and Unfallible Imams.
Umrah Mofradah has been mentioned in authentic Hadeeths and reward of it is the forgiveness of all the sins.
'Wassalam.