C programming isn't that hard. But it requires enough work at the beginning. Fortunately, I'm with you and we have a very good friend since three chapters – our Arduino board. We will now go deep into the C language, and I'll do my best to be more concrete and not abstract.
This chapter and the next one are truly C language-oriented because the Arduino program design requires knowledge in programming logic statements. After these two chapters, you'll be able to read any code in this book; these strong basics will also help you in further projects, even those not related to Arduino.
I will also progressively introduce new concepts that we will use later, such as functions. Don't be afraid if you don't understand it that well, I like my students to hear some words progressively sometimes even without a proper definition at first, because it helps further explanation.
So if I don't define it but talk about it, just relax, explanations are going to come...