"I have seen that matlab function like this function dx = some_name(x, u, p) is called as following model = @some_name;"
That syntax does not call the function.
A function handle is a fundamental MATLAB class: https://www.mathworks.com/help/matlab/matlab_prog/fundamental-matlab-classes.html
A function handle creates an object which can be handled just like any other object (e.g. a numeric array, cell array, graphics object, etc.), e.g. passed as an input/output argument or within a function or script. It can be evaluated when required, just like the original function:
fnh = @sin;
fnh(pi/4)
