Transposing rows of data into columns of data

Try this

Sub abc()
 Dim i As Long, ii As Long, n As Long
 Dim a, x, aValues
 
 ReDim aValues(1 To Rows.Count, 1 To 3)
 With ActiveSheet
    a = .Range("a3", .Cells(Rows.Count, "c").End(xlUp))
    For i = 1 To UBound(a)
        x = Split(a(i, 2), ",")
        For ii = LBound(x) To UBound(x)
            n = n + 1
            aValues(n, 1) = a(i, 1)
            aValues(n, 2) = x(ii)
            aValues(n, 3) = a(i, 3)
        Next
    Next
 End With
 Worksheets.Add
 With Range("a1").Resize(n, UBound(aValues, 2))
    .Value = aValues
    .Borders.LineStyle = xlContinuous
 End With
 
End Sub