This is a Singapore Government Disembarkation/Embarkation Card (D/E Card) which travellers must complete and submit together with their passports to officers of the Singapore Immigration Department, when they seek permission to enter Singapore.Note that it requires travellers to state "MA:LE" or "FEMALE":
In Australia on the other hand, passports can be issued " to sex and gender diverse applicants, identifying them as M (male), F (female) or X (indeterminate/intersex/unspecified)."
So, what happens then when someone who is identifies as "indeterminate/intersex/unspecified" attempts to enter Singapore? A choice must be made, and it must match that stated in the passport. To do otherwise is likely to be considered a crime. The same is likely to apply in almost all if not all other Asian countries.