Is 12 am morning or night?

No such time as '12 am'.

It is '12 noon' (midday) or 12 midnight.

'am/pm' are the Latin initials for 'ante/post merdian' , which means 'before/after noon'.

So if it is '12 noon', how can it be 'am/before noon'. It is NOON. '12 am' or '12 pm' is a confusing nonsense.