Young Mula=Young Money
Young Money Entertainment is an American record label founded by rapper Lil Wayne including artists:
Lil Wayne
Mack Maine
Drake
Nicki Minaj
Tyga
Gudda Gudda
T-Streetz
Jae Millz
Lil Chuckee
Shanell
Lil Twist
Cory Gunz
Jay Styles
Short Dawg
T-Pain
Torion Sellers

When he says "Young mula baby" he is saying his record label