How the singer commands the stage: body language, audience contact, movement, facial expression.
Practice in front of a mirror. Try three levels: static (just singing), medium (stage movement), dynamic (dance, interaction).
The audience 'eats with their eyes' — 80% of perception is visual. Even perfect singing loses impact if the singer stands like a statue.
Mick Jagger, Freddie Mercury — movement was part of their performance, not an accessory.