The official courseware for CCSK assumes that you, the learner, has some background in IT. As CSA states:
"We recommend attendees have at least a basic understanding of security fundamentals, such as firewalls, secure development, encryption, and identity management".
Other than that, I find there are sometimes other gaps in the knowledge of learners.
The units in this section will provide you with some preparatory material. If you are not familiar with what is described in them, you will have a hard time understanding some of the body of knowledge.
There is also additional material in each of the following sections, woven into the flow, for example on SDN.
Additionally, here are some WikipediA articles that could be helpful (small tip: most of them also have translations in other languages).