Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Indonesia to Bahrain as you normally would.
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 Manama Bahrain Intl Airport flight would often be abbreviated as a DPS to BAH flight. While you’re still figuring out your travel plans, it’s not a bad idea to learn the names and codes of other airports around these areas: Jakarta Soekarno-Hatta Intl Airport (CGK), Surabaya Juanda Airport (SUB), Praya Lombok Intl Airport (LOP), Medan Kuala Namu Intl Airport (KNO), Yogyakarta Intl Airport (YIA).