Problem with the Start() function

My question is quite simple:
why is AfficherGrille underlined in red in the void Start() function?

void Start()
    {
       AfficherGrille();
    }

    void AfficherGrille()
    {
        for (int i = 0; i < 8; i++)
        {
            string row = "";
            for (int j = 0; j < 8; j++)
            {
                row += grid[i, j] + " ";
            }
            Debug.Log(row);
        }
    }

Voici une image:

Thanks for your help,

A+

Read the error message: it is telling you it is ambiguous between two different functions of that name (AfficherGrille).

Look at your other function by this name and either rename it or otherwise make it unambiguous.