The Single Leg Romanian Deadlift (RDL) or Unilateral Deadlift is an exercise that works the posterior chain. It's one of the multiple variations of the Deadlift, the one shown here specifically is performed with dumbbells and the rear foot in a higher place.
It is a great exercise for the hamstrings hypertrophy and increasing the posterior chain pulling strength.
The main difference from the normal Deadlift to the Romanian Deadlift is the range of motion, as in the RDL the weights shouldn't go lower than the mid calf height. This way you will keep the tension through all the time.
As said previously the Romanian works the posterior chain muscles. These muscles are: