Sungei Buloh Wetland Reserve (https://www.nparks.gov.sg/gardens-parks-and-nature/parks-and-nature-reserves/sungei-buloh-wetland-reserve) or the MacrRitche treetop walk (https://www.nparks.gov.sg/gardens-parks-and-nature/parks-and-nature-reserves/central-catchment-nature-reserve/treetop-walk) if your friend is an outdoorsy person.
For food, go out to one of the more local hawker centres and just wander around. Or research first on one of the local foodie blogs to see what you want to try. http://ieatishootipost.sg/ is a good start.
