This is a minor issue and it will not cause you any problems on the PMP exam.
But the answer to your question is very unsatisfactory: Nobody agrees on what the P in PMO stands for. About 50% of project managers says it stands for "Project" and the other 50% say that it stands for "Program".
(I also heard project managers say that PMO stands for "Piss Me Off" or "Provides More Opportunity"...
In the end, the question isn't what the P stands for but what the PMO actually does. So as long as you understand what the function of a PMO is according to the PMBOK Guide then you will do just fine.
The PBMOK mentions in section 1.4.4 PMO as Project Management Office and in the glossary also the term PMO and Project Management Office are mentioned. This makes me believe that PMBOK assumes P in PMO as Project.
The episode E01.04 Introduction to Project management mentions PMO as Program Management Office, please explain why?
If for the exam we have to refer only PMBOK terminology then I am confused about why PMO is referred as Program Management Office in the exam preparation courses.
The slide could have mentioned PMO as Project Management Office and could have added some more description like there are many views for PMO and some people also see it as Program Management Office but PMBOK views it as Project Management Office.
These are my views, please guide me with your views. I have just started studying with the new version of Video Prepcast.