Saturn is at home in the 10th house, which rules profession, public image, reputation, and social status. The cusp of H10 is the angle called the Midheaven (MC), which represents one of your parents (traditionally the mother, in modern astrology the father). Saturn in Sagittarius transiting the MC can coincide with a crisis for one of your parents. Its transit through your H10 brings up challenges involving your career and image.
If you have Saturn in your 10th house currently, you have a Scorpio or Sagittarius midheaven. Scorpio midheavens are secretive and controlling about their profession and image, and have a magnetic quality, but may be manipulative. Saturn’s presence can force you to re-evaluate your approach; perhaps you are a control-freak when it comes to your social media image, preventing you from being seen by the right network of people, or maybe former manipulative behavior has damaged your professional reputation.
Sagittarius midheavens are happy-go-lucky in their image, and competitive in their profession, even if it’s all a game. If you have this MC you may have multiple possibilities for your career, and enjoy foreign travel as part of your profession. Saturn’s presence may alert you to how your public image online has damaged your professional life (too many party pictures, for example), or maybe you haven’t taken your career seriously enough and must make some realistic decisions.
Saturn transiting H10 will require both of you to decide if your current profession and your reputation (including social media image) are in-line with your beliefs, but also if your career provides you with opportunities for growth and expansion. If not, changes may have to be made.