His passive and W allows for zoning & poke, whether it be defensive or offensive, and synergies with a lot of items(Rylai's, Liandries, Luden's, etc) and he can farm safely from a distance. Although he is a bit strange and takes a little bit of getting used to.
His Q gives him reliable hard CC & damage. And the fact that it grows the farther it travels sets up great plays(maybe even full-team stuns if it can grow large enough).
His E gives him bonus movement speed & the ability to go over terrain. It's somewhat like Bard's Magical Journey except he can't take teammates, but he can travel half the map with ease.
His ult is another source of(depending on where your enemy is) reliable CC with a good source of damage that's good for engages or disengages.
All this makes him capable of many roles. He can go tank-mage/juggermage like Vladimir or Cho'Gath in top-lane, an AP off-tank mage in mid(his intended role), a Cinder or Runic-Echoes jungler like Gragas, or a poke support like Sona or Zyra.
And, because you're a new playing and probably don't know this, Aurelion Sol's based off another champion that was announced in 2013, Ao Shin. He was supposed to be released in 2014 or 2015, but never got into the game until he developed into Aurelion Sol.