If you googled, you will find that while Airbnb is itself legal in Singapore, short-term rentals of residential properties are not, with some exceptions. This means that renting out your property for less than 3 months for private residences or less than 6 months for HDB flats is generally illegal. Serviced apartments fit your requirement, but you will still have to check that everything is above board. When you find something suitable, check that the property is not rented out to you illegally.