Two statements I don't understand

[Bruin 1953]

I recently visited this MSDN page:
http://msdn.microsoft.com/en-us/library/6x627e5f.aspx

Found this code:


For i As Integer = 0 To TestArray.Length - 1
If TestArray(i) <> "" Then
LastNonEmpty += 1
TestArray(LastNonEmpty) = TestArray(i)
End If
Next

I don't understand the statements:
TestArray.Length

and the statements:
LastNonEmpty += 1

Any help!