This is the 11920th most frequent Russian word.
засветилась
"Засветилась" means "lit up" or "became visible/exposed."
Here, 'засветилась' means 'appeared and gained attention', something related to showing up in a movie which provided visibility/exposure.
Она засветилась в новом фильме.
She appeared (hit the spotlight) in a new movie.
In this context, 'засветилась' refers to the light bulb emitting light when powered.
Лампочка засветилась, когда включили свет.
The light bulb lit up when the light was turned on.
Here, 'засветилась' indicates the car was illuminated or lit up due to the headlights shining on it.