In 1957, Malaya was a significant year for philately due to its independence (Merdeka) on August 31st. This led to the release of new pictorial stamps and corresponding First Day Covers (FDCs).
The most prominent stamp issue in Malaya in 1957 was for its independence on August 31st. These stamps often depicted themes related to the new nation, such as the Coat of Arms, Flag, and Map of Malaya.
  Johore was one of the Malayan states, and as such, FDCs from 1957 mostly cancelled in Johore Bahru (the state capital) and sent to or from Johore. 
 A "private" FDC refers to a cover not officially produced by the postal authorities but created by individuals or stamp dealers. These often feature custom designs (cachets) or special arrangements to commemorate the stamp issue. They can vary widely in design, quality, and scarcity.
 This is a well-designed and visually pleasing cover.