What tutorial are you following?

tutorial 51: Menu class in the SFML course

Can you show us your code/

//Main Menu header file

#ifndef MAINMENU_H
#define MAINMENU_H
#include <SFML/Graphics.hpp>
//#include "MainMenu.cpp"
//Cyber Pong main menu
class MainMenu
{
private:
    int selectedItemIndex;
    sf::Font font;
    static const int Max_Items = 3;
     sf::Text menu[Max_Items];
public:
    MainMenu(int width, int height);
    ~MainMenu();
    void draw(sf::RenderWindow &window);
    void move_up();
    void move_down();

};
#endif // MAINMENU_H

//Main Menu.cpp

#include <iostream>
#include "MainMenu.h"

//menu constructor
MainMenu::MainMenu(int width, int height)
{
    if(!font.loadFromFile("fonts/arial.ttf"))
    {
        //Handle font error
    }
    //menu list
    menu[0].setFont(font);
    menu[0].setColor(sf::Color::Green);
    menu[0].setString("Play");
    //divide the width by 2 and height by the max number of items on list
    menu[0].setPosition(sf::Vector2f(width/2, height/(Max_Items + 1) * 1));

    menu[1].setFont(font);
    menu[1].setColor(sf::Color::Green);
    menu[1].setString("Options");
    //divide the width by 2 and height by the max number of items on list
    menu[1].setPosition(sf::Vector2f(width/2, height/(Max_Items + 1) * 2));

    
    menu[2].setFont(font);
    menu[2].setColor(sf::Color::Green);
    menu[2].setString("Exit");
    //divide the width by 2 and height by the max number of items on list
    menu[2].setPosition(sf::Vector2f(width/2, height/(Max_Items + 1) * 3));
}
//menu destructor
MainMenu::~MainMenu()
{
}

//draw main menu list
void MainMenu::draw(sf::RenderWindow &window)
{
    for(int i = 0; i < Max_Items; i++)
    {
    window.draw(menu[i]);
    }
}

            
//  In my main.cpp

  sf::RenderWindow window(sf::VideoMode(gameWidth, gameHeight), "Pong!");

//create menu object as type Mainmenu
  MainMenu menu;
  menu(window.getSize());

So the gameWidth = 800 and height = 600. I get the error at menu(window.getSize());

Where is that line I can’t see it?