Saturn represents structure and responsibilities: limits, efforts that take time to bear fruit, learning through experience. The sign it occupies describes a style of discipline — demanding and rigorous, patient and cautious, or any other nuance depending on the sign.
Saturn has a bad reputation, but its function is structuring: it is the planet that gives lasting consistency, where others give the momentum of the moment.
Domicile: Capricorn and Aquarius. Exaltation: Libra. Detriment: Cancer and Leo. Fall: Aries. Saturn is a diurnal planet — its sect strength is at its peak in a chart born by day.
Saturn finds its joy in the 12th house (isolation, inner trial, what is gone through alone).
The Saturn return, around age 29-30 and again around 58-59, is one of the most studied passages in predictive astrology — see the technique already available on this site.