Llevar puesto means "to have on" or "to be wearing": "She has on an elegant coat" or "She is wearing an elegant coat."
Unfortunately, Duo does not accept "She has on an elegant coat." Reported 19 June 2019.
EDIT: Duo accepted "She has on an elegant coat" today, 20 June 2019. That was very fast if it was a correction in response to my report. It's possible I had a typo somewhere in my sentence, or someone else had reported earlier (thanks, if so!).