Stand is one of the first things I teach them during the training to lead: come, stand, whoa (this is different from stand because it only means stop, not stop and stay) and staying beside me.
First only a few seconds standing, combined with the command, then a longer period. First with me standing right beside them, then with me moving around them, touching them.
It takes some time and much repetition and praise.
The tricky point is to anticipate when the goat will move again. Look closely for telltale signs like small muscle contractions, shifting of weight and repeat/reinforce the command BEFORE the goat moves. You can reinforce either with a shift of your body, your position, a slight tug on the lead - depends on the goat.
For the first lessons, I ask only seconds, so that standing is more a natural position than a trained response until they get the idea of what the command means.