Hi I get these 2 reports when I open the program in Unity What does that mean?

Assets/Scripts/Public/CSVFileTool.cs(5,14): error CS0234: The type or namespace name Data' does not exist in the namespace System’. Are you missing System.Data' assembly reference? Assets/Scripts/Public/CSVFileTool.cs(17,9): error CS0246: The type or namespace name DataTable’ could not be found. Are you missing an assembly reference?

You should name the public class of the script the same as the name of the script, that should solve the problem.