Imagine system as a box which in which a process is completed. Every system is solving a larger problem, and can be broken down into smaller problems that can be solved and assembled. Sort of like a Lego set! Each small process has 'logic' as the backbone of the solution. Logic, can be expressed as an algorithm and implemented in code. As learnt in Chapter 1, The World around Us you can design a system to arrive at solutions to a problem.
Another advantage to breaking down a system into small processes is that in case your solution fails to work, you can easily spot the source of your problem, by checking if your individual processes work.