This is the 10952nd most frequent Russian word.
выставлены
"Displayed" or "exhibited."
In this sentence, "выставлены" is used to indicate that the paintings were presented for viewing at the event.
На выставке были выставлены картины известных художников.
At the exhibition, paintings by famous artists were displayed.
Here, "выставлены" conveys the idea of setting or placing the prices at a certain level.
Цены на товары в магазине были выставлены слишком высоко.
The prices of goods in the store were set too high.
In this context, "выставлены" implies that the works are presented or shown to the public.