Only the *Xilinx* blocks can be translated into FPGA code.
The Simulink blocks are typically only used as source (provide simulation data) and as sinks (display results).
Simulink block are connected to Xilinx blocks by means of 'gateways', which are basically 'convert' blocks (typically floating point to/from fixed point). You can think of gateways as the physical pins of the FPGA. Simulink provides, and reads, the data to/from these 'pins'. This does not only work from within the Simulink environment, but this also works when the Xilinx blocks are translated into FPGA code, and you let the simulation run in the actual FPGA hardware (Harware Co-simulation).
You can also use MatLab M-Code (Xilinx M-Code block), but this is limited (only basic logical constructions like if/then/else/case, basic mathematical functions like compare/add/subtract/mult(?)). This can be used, for example, to contruct state machines.