I just had one query regarding sequence points, I studied it on wikipedia , this statement that

"Before a function is entered in a function call. The order in which the arguments are evaluated is not specified, but this sequence point means that all of their side effects are complete before the function is entered. Note that a function call f(a,b,c) is not a use of the comma operator and the order of evaluation for a, b, and c is unspecified."

So please explain this statement ,when comma operator is a sequence point then its order of execution is defined so how is it saying that order of evaluation is different.

I had studied earlier that a function call is executed through stack involvement ,hence all the arguments are pushed in stack and hence  from right to left ,the arguments are pushed into stack ,so basically how does the function call takes place,is it that after the argumets if they involve any expressions say f(a*b,8) where a and b have particular values is subtituted,before the arguments is actually passed to function.