Cannot implicitly convert type "string" to "int": C# Error

I’m trying to use the EditorGUILayout.Foldout thing on a custom editor, and it requieres a bool and a string:

expand = EditorGUILayout.Foldout(expand, reference.Lines[x]);.

I already checked it, and the references and declarations and they are okay:

Dialogue reference = (Dialogue)target; //inside Dialogue Script public string[] Lines;

But it still gives me the following error: Cannot implicitly convert type “string” to “int”.

Have a Nice Day!

Afterall, x was not an int.