Saturn represents, time, limitation, boundaries, law, structure, authority (along with the Sun) discipline, karma, old age, bascially it's your obstacles in life, things which restrict you or place limitations on you, limitations in the form of health, poverty, relationship, family etc etc.
All of us are under Saturn's influence as long as we are incarnated in this physical world and we all have limitations until we are Gods, all of us have things we are incapable of doing. Even if you are a billionaire, even if you are a super model, even if you are a martial arts expert, even and even and even and even until tomorrow, wherever you are at you still have some limitation. Some have more limitations than others depending on the conditioning of their soul but either way we're all limited. The nature of the physical world is limitation, defined boundaries. Saturn in your astrology chart shows you where your limitations are at. What you will experience as limiting.
Life is about overcoming these limitations as best as we can and in doing so we improve our souls, evolve to a higher spiritual level, more power, awareness and hopefully improve the world around us and life as a whole. Physical and Spiritual mastery, becoming as Gods.