Yoga has many poses with one leg forward. This pose helps prepare for them.
First get good at the stand pose and then the pillar pose.
Align
Start from the stand pose.
Have your feet wider apart than your hip joints but not wider than the outside of your hips.
Shift all your weight to one leg into the pillar pose. Keep your pelvis level and feel the three points of contact under your weighted foot. And pause.
Feel your unweighted foot very soft on the floor. Without turning your pelvis slide your unweighted foot forward about a foot length, feeling it in light contact with the floor.
Put your weight even on all six points under both your feet with both your legs straight but not locked, knees soft. Keep your pelvis and torso vertical. As in the stand pose, turn your thighs out slightly and push your pubic bone forward a little. And pause.
Bend your forward knee and keep your weight even on all six points under both your feet. Keep your pelvis and torso vertical. And as in the stand pose, turn your thighs out slightly and push your pubic bone forward a little. And pause.
Return to your legs straight but not locked, knees soft, and with your weight even on all six points under both your feet. Pelvis and torso vertical with your thighs turned out slightly and your pubic bone pushed forward a little. And pause.
Shift all your weight to your back leg and slide your forward foot back to the pillar pose. Pause.
Return to and pause in the stand pose. Then shift your weight to your other leg, stand in pillar on that side, and slide your other foot forward and do the pose. Then center in the stand pose and do both sides again.