When flying from Siargao Island to Malaysia, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.
These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Del Carmen Sayak Airport to Kuala Lumpur Intl Airport flight would often be abbreviated as a IAO to KUL flight. Kota Kinabalu Airport (BKI), Penang Intl Airport (PEN), Johor Bahru Sultan Ismail Intl Airport (JHB), Kuching Airport (KCH), Langkawi Airport (LGK) are other airports near this flight route and their unique identifiers/IATA codes.