This finger exercise is one I learned at one of my early piano lessons, many moons ago. It's a hand exercise to strengthen those musical fingers, especially our very weak finger #4.
Practicing Music 101 - Warm Up Stretches
One area that music students (as well as working musicians!) tend to ignore is stretching. Musicians are, in fact, small muscle athletes. It is important to take care of those delicate muscles that we have, not only to prevent repetitive strain injuries, but to ensure that we can enjoy making music for many years.