I'm a c++ beginner, so I have a lot of questions.

//#include <iostream> // sin, cout is defined in iostream.
#include <string>
using namespace std;

class Ingredient {
    string name[6] = { "Kimchi", "Egg", "Ham", "Potato", "Cheese", "Tuna"}; // If you know vector, it is better to use vector<string> name. Or use array<string, len> name.
 /* It is preferable to initialize in the constructor.
Ingressive::Ingressive():name({"Kimchi", "Egg", "Ham", "Potato", "Cheese", "Tuna") {};
*/
public:
    Ingredient();
    voidgetName(); // It would be more appropriate to rename the function to printNames.
    stringsetName() { return name[6];} // It would be more appropriate to rename the function to getName
    // It is recommended that you replace string&getName(intindex) {return name[index];}.


};

Ingredient::Ingredient()
{
    cout << "Materials";
}

void Ingredient::getName()
{
    cout << ": ";
    For (inti = 0; i < 6; i++) // It is preferable to use it as a constant instead of literal
    {
        cout << name[i] << " ";
    }
    cout << endl;
}

class Combin : public Ingredient
{
    string names[15] = { "Kimchi pancake", "Budae jjigae", "Potato sujebi", "Fried rice", "Tuna jjigae", "Omurice", "Gratin", "Cheese ball", "Tuna mayo rice", "Potato croquet",
    "Sandwich", "Rice burger", "Fried potatoes", "Potato soup", "Tuna kimbap"};
public:
    Combin();
    string calc(string name);
};


Combin::Combin()
{
    cout << "Choose two things you like from among them.";
}

string Combin::calc(string name)
{
    String n, a; // It is better to let the name know what is stored in the same way as ingredient_1, ingredient_2. 
                //If you do not want to change the stored value, it is recommended to use const.
    cin >> n >> a;
    for (int i = 0; i < 6; i++)
    {
        if (n == setName() && a == setName())
        {
            It is ambiguous whether it is cout << name[i] << name[i]<< endl; //string name or string name[6] inherited from Ingridiant.
        }
    }

    {
        for (int i = 0; i < 6; i++)
        { // name is a private member of Ingridiant and cannot be accessed from Combin.
        // If you want to access it, use protected! Or create and use the accessor string&getName(intindex).
            If (name[0] && name[i + 1]) // && operator has a boolean type of operand. Thus, n == name[0] &&a == name[i + 1]
                cout << names[i];

        }

        for (int i = 0; i < 4; i++)
        {
            if (name[1] && name[i + 2])
                cout << names[i + 6];
        }

        for (int i = 0; i < 3; i++)
        {
            if (name[2] && name[i + 3])
                cout << names[i + 10];
        }

        for (int i = 0; i < 2; i++)
        {
            if (name[3] && name[i + 4])
                cout << names[i + 12];
        }

        if (name[4] && name[5])
            cout << names[14];
    }
    Cause of return 0; // error, if return is set to string, it must be returned to string.
}

int main()
{
    string d;
    Ingredient i;
    i.getName();
    Combin c;
    c.calc(d); 
}