The two figures are downstream and upstream, and which way round they are depends on how the particular modem reports them.
There's no 'good' or 'bad' value, it depends on the condition of the connection and what you want from it. Larger values will give you lower speed and greater stability; smaller values will give you higher speed and less stability. That's an over-simplification of course. 6 dB is a typical initial target SNRM, and is generally considered a sensible value.
