I believe this is part of the city's ongoing effort, predating Hurricane Sandy, to restore the deteriorated seawalls along Jamaica Bay in this section of the Rockaways. (That's a Seastreak ferry from Manhattan speeding by in the background.)
Several contiguous lots on this street now lie vacant, their Sandy-destroyed homes having been bulldozed.
This is located in the prayer garden of St. Francis De Sales Church. The plaque on the left and the cross above it, made from World Trade Center steel, are dedicated to the victims of 9/11, twelve of whom were parishioners here. The plaque on the right commemorates the lives lost, including those of five more parishioners, in the crash of American Airlines Flight 587.
This synagogue celebrated its 90th anniversary last year, six months before Hurricane Sandy flooded its ballroom, chapel, and everything else in the basement.