Having a stable/strong musculature around the pelvis is important for lower back health. In every step the gluts need to counterbalance your body weight to keep the pelvis level with the horizon. If these muscles are weak the pelvis will not stay horizontal, and the very foundation of your spine drops lower on one side which causes undue stress on your spine as it must compensate and bend to keep the torso upright.
The side plank/clam is a good functional exercise to strengthen the muscles that stabilise the pelvis.
To perform the exercise, lie on your side with both knees and hips bent to about 60 degrees. Use your bottom elbow to prop your torso up off the ground.
Then lift your pelvis off the ground, straighten your hips and separate your knees in one move. You will end in a position where only one forearm and the same side shin/knee touch the floor.
After that revert to the starting position. Repeat for 8-36 reps on each side depending on your strength level.