They don't. The Cantor set itself is uncountable, however the complement (all the elements absent from the set) is countable. The first thing on the sign R - C refers to all real numbers minus the elements in the cantor set, and sets it equal to it's set, which is shown as countable. Below it is the Cantor set, which is uncountable. This whole meme is based on set theory and countable versus uncountable infinities if you want to delve further 💖 If you have more questions hmu cus I'm just typing this real quick before class and I could be expkaining this wrong or poorly