What is called that place?

Function Room (if indoors)

"What is this place called?" A banquet hall.

The self-service table is called a “buffet” (bufFAY), and sometimes that can be applied to the whole space, depending on the circumstances.

The space, if it is (or can be) rented, is sometimes called a “function hall.”

It looks like it's outside so I would call it a pavillion.

It looks like it opens up directly to the outdoors. If that's true for all walls then I would call it a "pavilion." But since the photo seems to be focusing on the tables and food maybe I'm looking beyond the mark.

Halls and Rooms are used for interior spaces only. This appears to be an outdoor space. I'm not sure the place has an exact name, but it could be a "buffet table" or "snack bar". You could also say it is inside whatever structure it is, like a "tent", "awning", or "pavillion".

Table

I’d call it a wedding venue.

We use our auditorium

I see others have given you answers, so I just want to note that the correct way to ask this question is “What is this place called?” or even just “What is this called?”

The English syntax in your question should be “what is that place called?” or, if you wanted to name the direct object last, “what would you call that place?” This is also a classic case of the place being identified differently than the event that you see happening. The place might be called a pavilion, reception venue, or even gazebo (depending upon the size of the venue; gazebos are typically smaller but I’ve still heard it used), since this appears open to the outdoors. It’s unlikely it would be called a reception hall or banquet hall, as halls are usually indoor venues. I would probably go with pavilion, personally.

Buffet table? The social event in the background looks like a wedding reception.

Conference room. https://www.mercuremanchester.co.uk/meeting-rooms-manchester/our-meeting-rooms/

The Fucking Catalina Wine Mixer

Function room? Event space?

I don’t really know of any office buildings that just have dedicated party rooms. Usually you would hold an event like this in a rented banquet hall or restaurant or appropriate a break room or meeting room for the event.

“What is this called?” “What is called that place?” Sounds… clunky. To answer the question it’s a banquet hall.

Banquet

For this specific image I would probably call the open sided structure a pavilion.

Banquet hall would be a good one. That's quite common. A "reception hall" would be another, as we sometimes call these events "receptions" (especially after weddings and such). A bit more generic, but also encapsulates this would be a "party venue". Definitely not a "break room" though (unless this is just an incredibly fancy example of one =p). Those are the usually simple rooms, sometimes with basic kitchen equipment like a fridge and microwave, where employees take their midday break from work.