South Node – this represents many things. Let’s start with familiarity. There’s familiarity with anger, acting on your desires, sexual urge, fighting, asserting yourself, competing with others. Equally, there’s courage, resourcefulness and the survival instinct.
Familiarity would suggest that you are pretty good, actually excellent in any of those things, especially if Mars is dignified i.e. in Aries, Scorpio or Capricorn or in Pisces (by triplicity although this is contentious). It’s very likely that you have a natural aptitude for what was mentioned above.
However, staying in one’s comfort zones aren’t necessarily the best for personal and spiritual growth. Be a warrior. Take the first step out into the unknown territory!
P.S.: Naturally, Mars would opposition North Node as well. It’s an opposition, there’s some kind of balance and reconciliation involved. You can’t just stop fighting, stop acting on your desires, etc. You do it when it makes sense and capitalize on what comes naturally to you to work on your North Node qualities.