How do read this C++ statement

I'm currently going through C++ primer Plus by Prata and came across this statement regarding *this pointer:

const Stock &topval(const Stock &s) const;

Giving that Stock is a class and topval a function ,

How do you read this statement?

I tried using the clockwise/spiral approach but I get confused by all the const. I believe that understand how to read it will allow me to better understand the concept that it is trying to prove.

Thanks!