hand.h

#ifndef HAND_H
#define HAND_H

// string is not IO.
#include <string>

// For random
#include <cstdlib>

class hand
{
  public:
    hand();
    std::string getType() { return type; };
  private:
    std::string type;
    static std::vector<std::string> types;
};

#endif

main.cpp

// put this somewhere else
// and no ; after an include!
#include "hand.h"
#include "player.h"
#include <string>
#include <iostream>
#include <cstdlib>
#include <ctime>

std::vector<std::string> hand::types{"rock", "paper", "scissors"};

hand::hand()
{
    // Initialise with a random seed somewhere earlier, not every time you make a hand.

    // Random number from 0 to 2
    random = std::rand() % 3;
    type = types[random];
}

int main(int argc, const char *argv[])
{
    std::srand(static_cast<unsigned int>(std::time(0));
    hand h;
    std::cout << h.getType() << std::endl;
    return 0;
}