PACE units link your study with the 'real world' and most involve internships. Every Macquarie undergraduate degree requires you to complete at least one. Some have research projects, fieldwork, stimulations, etc.
So a PACE unit may involve you doing a research science project at a local school, working on a project for a company, etc.
I suggest you email the PACE faculty who can directly answer your questions.
On a side note, PACE may not seem like alot of fun but you can put it on your resume at the end. Go in with an open mind, and be prepared to apply what you've learnt in your degree to it!
Having done ACCG315 it does not require you to do an internship. It's pretty much reflecting on your previous accounting units (only theoretical not practical).
Pretty much you'll do a weekly reflection, a personal case study (business report) , group business report and also a 10 minutes presentation (in a group) without any notes. You'll meet some individuals within the industry who will tell them about their career (which you'll be reflecting on), learning about new exciting changes in the industry(woo blockchain) and presentation skills. Pretty simple unit, wouldn't stress to much.