What is 12 pm in military time?

Are we talking of 12 noon or 12 midnight. 'pm' means 'post meridian' (Latin) for 'afternoon'. If it is 12 noon it is neither before nor after noon , it is 12 NOON. A similarl argument holds for 12 midnight.

'am' are the Latin initials for 'ante meridian ' ; before noon'.

In military time ; 12 noon is 1200 hrs.

12 midnight is NEVER used because of confusion over the date/day . The time of '0000' and '2400' is the same instant.

So to avoid confusion the earliest/latest times used are 0001/2359 hrs respectively.