A spotlight was a type of lamp used to illuminate performers and athletes. One who focused spotlights on others was called a spotlight operator.
In 2373, Quark ordered the computer on Deep Space 9 to turn on a spotlight in Quark's Bar. (DS9: "Rapture")
In 2376, the tsunkatse arena on Penk's starship was lit by spotlights. (VOY: "Tsunkatse")
Metaphorically, to be in the spotlight was to be the subject of attention. In 2155, T'Pol and Trip Tucker suggested that Jonathan Archer and Enterprise NX-01 should have received some of the attention being given to Nathan Samuels as the Coalition of Planets was taking shape. Archer declined, saying, "Samuels likes the spotlight, and he's welcome to it." (ENT: "Demons")
In 2374, following Odo's singing performance, Vic Fontaine asked the changeling how he liked being in the spotlight. Odo replied it was "very bright". When asked to elaborate, he said he supposed the lights in his eyes kept him from seeing the audience and being nervous. (DS9: "His Way")