[chrismorgan]

I’ve come across it in various largely-Americentric writing and figured out the concept, but yeah, it’s not something I’ve seen practised in Australia.

It means “I will always be available in my office during such-and-such hours every week, for anyone to come and talk to.” I think it’s normally a walk-in affair rather than involving making appointments. First come, first serve, but now you don’t have to go through the bother of making appointments and such and comparing your timetables. Makes life easier for both parties. This article is talking of making appointments, but most of the benefits still remain of having a known block of availability.

[chalst]

It's common in Germany, called "Sprechstunde" ("speaking hours").

[jq-r]

"Consultation hours" in some EU countries.

[simonw]

That's a better name for it than "office hours" I think!