How does Uranus' tilted axis affect its seasons?
A hell lot.
Since Uranus has an axial tilt of 98°, it is essentially spinning like a ball, forward and around the Sun.
On Earth, we have an axial tilt of 23°, which gives us our familiar seasons of spring, summer, fall, and winter. When the N. Hemisphere is tilted towards the sun, it's summer, when it's tilted away it is winter, both last about 3 months.
However, on Uranus, you have, basically, an entire hemisphere facing the sun, and the other is pointed away. And since planets/moons/celestial bodies rotate around its poles, each of Uranus's season lasts 21 years, if you divide the orbital period of Uranus (84 earth years) by 4.
But general rules still apply to the seasons; summer is hot(but not by a lot since it is so far away from the sun), and winter is extremely cold.
I want to notify you the fact that we don't know much about this planet and only had a single, short flyby (Voyager 2) that was dedicated to studying the planet. Therefore, we could easily be wrong about any topics regarding Uranus.