'Turning on' is given as the translation, but only 'switching on' is accepted as an answer.
Swahili is currently in limited beta. It only came out two weeks ago and has lots of errors. If you see anything that doesn't make sense, make sure you report it. The report option is on the bottom left after you complete an exercise.
"is turning on the computer" is accepted but not "turns on". I suppose it's the same