The phrase "good command" means having complete control or mastery over something.
Sentences with «good command»
She made sophisticated, aesthetic paintings with good command of light, shadow and technical skill. (en.wikipedia.org)
Well, I believe strong analytical skills, good command on mathematics and attention to detail are must haves for any person in the role of a payroll officer. (coverlettersandresume.com)
Start out where your dog sees you hide the item, then repeat over and over, «Find or Seek» are good commands for this exercise. (barkbusters.com)