i don't understand these code,please help me

i using hdlcoder to convert adaptive filter to vhdl and vhdl testbench,but some part of them i don't understand

here

SIGNAL Product_mul_temp                 : signed(47 DOWNTO 0);  -- sfix48_En33
  SIGNAL Product_out1                     : signed(31 DOWNTO 0);  -- sfix32_En20
 Product_out1 <= "01111111111111111111111111111111" WHEN ((Product_mul_temp(47) = '0') AND (Product_mul_temp(46 DOWNTO 44) /= "000")) OR ((Product_mul_temp(47) = '0') AND (Product_mul_temp(44 DOWNTO 13) = "01111111111111111111111111111111")) ELSE      "10000000000000000000000000000000" WHEN (Product_mul_temp(47) = '1') AND (Product_mul_temp(46 DOWNTO 44) /= "111") ELSE
      Product_mul_temp(44 DOWNTO 13) + ('0' & Product_mul_temp(12));

and here

SIGNAL Sum_add_cast                     : signed(32 DOWNTO 0);  -- sfix33_En20
  SIGNAL Sum_add_cast_1                   : signed(32 DOWNTO 0); 
Sum_add_cast <= resize(Product_out1, 33);
  Sum_add_cast_1 <= resize(Coef1_out1 & '0' & '0' & '0' & '0', 33);

im a beginner,so that many function that i don't know ,thanks for help