Visual studio has a feature to show some info about a function when you hold a mouse cursor over a name of a function in the code editor window.
Is there a way to show some hint about some of my own functions not only about library functions?
Yes - just comment your code with comments the places it expects and it should start showing them.
In the case of C++ code it expects a comment on the line above the function name in the .cpp file and/or the same in the .h file - personally I would always try for both as humans can also use these comments and find them there!
Expansion:
C++ Expects comments in C++ style i.e. // Comment
immediately before the function declaration - you can continue over more lines if all start with //
. N.B. Other languages may differ.