"Big feet" is a way of walking when training a puppy:
It is walking in a slow and steady way, feet swept in big half circles. Keeping the feet close to the ground.
By walking like this, the puppy will get nudged out of the way gently, you will not fall, and soon the puppy will learn where the safe spaces are to move around another.
It is big feet, not a big head, that create space in this world.