This exercise is not for beginners. It's somewhat complex and requires proper balance of both the dumbbells and the body because you are resting on top of an exercise ball. Thus, if you're beginner you should opt for classic bicep exercises involving the use of a barbell.
Having said the above, this exercise is very effective for your biceps and your core (mid-section) at the same time. The balancing aspect of this exercise will force your mid-section to work in order to keep balance. Thus, this movement has a dual-benefit: it targets your biceps while at the same time working and tightening your core.