First, I would strongly recommend you use Codeblocks, if you are on Windows. It will allow you to create a project, containing multiple .h and .cpp files, much easier.
First, for prots.h, you needed to include #include<iostream> at the top.
Secondly, for your prots.h, you declared two "void" function prototypes, but in your implementation, in functions.cpp, you changed their data types to "int". Changing them to void, pretty much fixed compilation problems. Also, adding "using namespace std;" in functions.cpp, allows you to use "cout" and "cin". Otherwise, use "std::cout" or "std::cin".
Here is the updated code, which should compile, in their respective files:
main.cpp, prots.h, functions.cpp, respectively.
//main.cpp
#include <cstdlib>
#include <iostream>
using namespace std;
#include "prots.h"
int main(int argc, char *argv[])
{
player player1;
player player2;
cout<<"Number 1 \n";
getinfo(player1);
cout<<"Number 2\n";
getinfo(player2);
cout<<"Number 2\n";
showinfo(player2);
cout<<"Number 1\n";
showinfo(player1);
system("PAUSE");
return EXIT_SUCCESS;
}
prots.h
#ifndef PROTS_H_INCLUDED
#define PROTS_H_INCLUDED
#include<iostream> // Needed to include #include<iostream>
struct player{std::string name; int age;};
void getinfo(player&a);
void showinfo(player&a);
#endif // PROTS_H_INCLUDED
functions.cpp
//fucntions.cpp
#include "prots.h"
using namespace std; // To make cout, and cin work.
void getinfo(player &a){ // Wrong data type
cout<<"ABOUT PLAYER \n";
cout<<"Name :\t";
cin>>a.name;
cout<<"Age :\t";
cin>>a.age;}
void showinfo(player &a){
cout<<"PLAYER INFORMATION \n";
cout<<"NAME :\t"<<a.name;
cout<<"\nAGE :\t"<<a.age;}