A Single Leg Deadlift is a great exercise for strengthening the hamstrings, glutes and ankles, whilst improving balance and core strength as well as working through the mobility of the hamstrings, improving flexibility.
We can do this exercise with either a Kettlebell or a Dumbbell. Start with your chosen weight in your right hand hanging down in front of you. Find your balance on your left leg, lifting your right leg off the floor. From here, hinge at the hips allowing the weight to come out in front of you and extending your right leg out behind you. Your position at the bottom of the movement should consist of your right arm at a 90 degree angle from your body with the weight resting lightly on the floor and your right leg extended straight out behind you as close to in line with your back as possible. Having hit this position, driving back up working through the same positions.
If you are finding it difficult to reach the weight all the way to the floor due to your hamstring flexibility, you can set up a raised platform for you to rest the weight on in that lowest position. This way you will still have the opportunity to regain your balance at the bottom of the movement.