Adopt a squat position against a wall with your knees and hips at 90 degrees.

Lift your heel up as high as you can. Keeping the other heel on the floor.

Make sure your back stays in contract with the wall.

Repeat as prescribed.

Repeat with opposite side.

Will help:

Hamstrings tendinopathy

Achilles tendinopathy

Achilles repair

Calf tear

Post-op knee rehab