how to handle multi line in test complete python script

I was not aware that those were array values, as you did not mention it. However, you will need to construct a string like so,

function test10()
{
    var L = [1, 2, 3];
    var U2 = ["A", "B", "C"];

    var str =
        "S2F33_DefineReport_Job: 'S2F33' W" +
        "<" + L[2] +
        "<" + U2[1] + "1> /* DATAID */";
        
    Log.Message(str); // Output string to see if format is correct
}

See https://stackoverflow.com/questions/7975005/format-a-javascript-string-using-placeholders-and-an-object-of-substitutions for substitutions values.