When flying from Bali to Tuvalu, 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 Denpasar Bali Ngurah Rai Airport to Funafuti Atol Airport flight would often be abbreviated as a DPS to FUN flight.