Yes. Think of "Hack" being the name and model of a computer manufactured by some small company that makes everything from the ground up. There is the Hack computer, which uses a Hack hardware architecture, which is based on a Hack CPU, which is based on a Hack ALU.
So where as we often talk about the Intel whatever-processor CPU, here we talk about the Hack CPU. Same for the ALU. An Intel CPU might have many different ALUs in it for different purposes and each one has some kind of a name so that we can keep straight which one we are talking about. Here we talk about the Hack ALU when we are talking about this specific ALU and not ALUs in general.