The above posts are exactly correct.
It's generally referred to as a '3 phase bank'. It can be on a pole (utility), inside of a building, built into switchgear, etc.
If you look inside of a 3 phase transformer, you'll see 2, or more likely 3 individual transformers. We don't normally call this a bank, (though technically it is), because they're all in the same enclosure.
Loadwise, there's no difference between a 3 phase transformer and a 3 phase bank of the same KVA and voltage rating.
A 3 phase bank can be somewhat tricky to connect, as polarity of each transformer must be correct, if not then the primary short circuit/overload protective device gets an actual field test!