Hi,
fixed point means not using the usual double precision variables but using integers (with a scaling and bias). A simple example would be an 8 bit unsigned integer with a scaling of 2^-4. This means you have 4 bits for the value (i.e. values 0-15) and 4 bits after the decimal point (means a precision of 2^-4 = 0.0625).
Read the corresponding section in the Simulink documentation on "Fixed-Point Data" in the section Modeling->Configure Models->Data Types->Concepts.
Titus
