"Objections to R & R" may be an exception to the "report and recommendations" of a master, hearing examiner or magistrate. If you could elaborate on the circumstance under which the phrase arises, a more specific answer may be possible. Perhaps, the clerk of the court will tell you what it is if you are a litgant in the matter. A clerk is not generally permitted to give legal advice, even to a pro se litigant, but telling you what "R & R" stands for is not in the legal advice category.
It sounds like someone in civil litigation, in some court, some where, is objecting to the report and recommendations of a magistrate judge. But if you are already represented by an attorney, you should direct the question to the attorney. If you are the litigant, you may want to seek representation. Your question does not provide much in the way of context.
I am not your attorney unless you and I have signed a retainer agreement. What I am saying is not legal advice. Do not act on this information without engaging my services, this is for consideration only.
Not exactly sure what you are asking. However, I believe it is the process of objecting (disagreeing) with the Magistrate's finding. You would have a certain amount of time to object in writing. The judge would then review the magistrate's report.