It's crunch time. The Sun in Capricorn is squaring Saturn in Libra which translates to restrictions (Saturn) on the ego (Sun). Even though the Sun is already obeying the rules in Saturn ruled Capricorn.
This can manifest in a couple of different ways. You conform (Capricorn) to the rules but still get pinched by social restrictions (Saturn in Libra). Or maybe you're a touch too ambitious (Sun) so you get your knuckles rapped (Saturn). It really is a boxed in kind of aspect.
Fortunately this influence doesn't last too long (it's exact on January 19th). Then the Sun will make a break for it into freedom-loving Aquarius. Relief. But for now, check out the areas of your chart where Capricorn and Libra are. This is where you'll be getting pinched, crunched and restricted. Probably unfairly. Since this influence has Saturn all over it, the best way to react is calmly and graciously. It won't be fun but you can make it so much worse if you kick up a fuss. Hard Saturn aspects can be very unforgiving.
Those with planets between 27-29 degrees Libra or Capricorn will feel this one most acutely.