Hey guys, does anybody know if one needs transit visa to fly through Singapore air port? A friend of mine flying from ktm to Australia via singapore airport. there is 12 hrs transit and wanna go out to the city if possible.

check the singapore government (foreign ministry) website.
So far, Nepalese are still provided with 2 weeks tourist visa at the airport to enter singapore.
This is my current understanding.

Singapore is one of the very few countries in the world where Nepali citizens do not need a visa for short visits.

Are there other countries besides Singapore that does not require visa for Nepalese passport holders?

You may be talking other than India.
"does not require visa or do not need visa" -this terminology is not correct. Visa is needed at any cost, but it is provided either at the airport on arrival or one have to obtain prior to departure.

Sri Lanka
Cuba

Thanks guys for your response. I will advise him accordingly.