F33 at 13.43

This is the pilot station "Seemannshöft" or also called "Lotsenhöft" for short.
F33 is a level indicator
"F" means high tide (flood); "E" = low tide.
The figures indicate the current water level in dm,
in this case 33dm or 3,3m above sea chart zero.
At low tide, red figures appear.