You can always use the general zapnout / vypnout (“switch on / off”) for any device. But for lights specifically, Czech has dedicated, more natural verbs.
1. Light ON: zapnout světlo = rozsvítit
rozsvítit is the special “make the light shine” verb.
Commands: Rozsviť! (to one person) / Rozsviťte! (plural or formal) — “Turn on the light!”
2. Light OFF: vypnout světlo = zhasnout
zhasnout is “to put the light out.”
Commands: Zhasni! / Zhasněte! — “Turn off the light!”
3. The Moravian twist: rožnout
Travel to Moravia and you’ll hear a completely different verb for switching a light on: rožnout.
Master rozsvítit and zhasnout for lights, keep zapnout / vypnout for everything else — and enjoy knowing rožnout as your little bit of Moravian flair.
Want to reveal all the secrets of Czech?
Regional words and the “right verb for the job” are the kind of detail that makes you sound local. That’s exactly what I teach in my online courses.
Check out the courses