The Arts and the Sciences are all the skills we learn and things we do related to making all the things. All of the stuff we use and consume and wear, all of the decorative bits we make and do that help us to recreate the past.
The Arts and Sciences is a massive set of topics spanning all of the cultures we like to learn about and all of the times before 1600 CE. Just when you think you might be getting a handle on a single topic you find out it is much bigger than you thought.
We have awards to recognize people for their explorations of the Arts and that Sciences, for what they learn and teach others. We have events dedicated to classes on any number of topics. The vast majority of the members of the SCA find the Art or Science topics that inspire them and they work on them at home, at local meetings and at events.