Saturn takes about 29 years to orbit the Sun, which means everyone experiences a "Saturn return" — Saturn coming back to the exact position it held at their birth — around ages 29, 58, and 87. It has a reputation as the astrological equivalent of a reckoning: relationships end, careers pivot, people "grow up" whether they want to or not.
Here's the part that's easy to miss: age 29 is also, independently, when a huge number of people go through exactly that kind of reckoning — first serious career reassessment, the tail end of a long relationship, the general shock of no longer being in their twenties. That transition happens on a very predictable human timeline, Saturn or not.
Saturn return isn't nonsense; the timing is real and precisely calculable. But most of what gets attributed to it is just what happens to nearly everyone in their late twenties, dressed up with a name. Knowing the name doesn't make the reckoning easier. It just means you saw it coming.