I found the series of comments below confusing, possibly because the lesson has been changed in between some of the responses being posted. According to Larousse «the former ... the latter (is)   le premier ... le second, celui-là ... celui-ci». That is, as the lesson states (Aug 23, 2020) ceci is the LATTER, cela is the FORMER. For the example in the lesson, this means (as makes sense) that the speaker is saying they prefer sleeping (the latter, ceci) to doing their homework (the former, cela). Both the definition from Larousse and the lesson are inconsistent with Shrey's answer below marked 'correct answer'. Both are in accord with the contributions of Diego and Alan, and their explanations that the sentence is not about 'this and that', but 'former and latter'.