A spotlight is a bright beam of light that shines on people on stage. Actors and rock stars love spending time in the spotlight when they’re performing, but if they’re famous they’re in the spotlight all the time.
If you star in the school play, you'll be in a literal spotlight, illuminated on the stage while you sing your big solo number. If some day you're elected President of the United States, you'll be in a figurative spotlight, at the center of intense attention by the public. You can also call this limelight. Lighting experts often call spotlights followspots.