This refers to a flimsy facade erected to impress someone.
In the late 1700s, Russian official Grigory Potemkin was in love with Catherine II. Potemkin was working to develop the Crimea region. When Catherine traveled there in 1787, Potemkin allegedly erected fake villages along her traveling route to impress her. Disputed legend has it that when she would pass a fake village, it would be disassembled then rushed forward and reassembled ahead of her, so she would pass it again.
The phrase has come to describe any bad situation that is artificially and haphazardly propped up to appear better than it is.