Do not buy from street vendors. They may look delicious but they are dirty, especially the drinks. Buy your food from the super market or from food chains. Street foods are delicious but if your stomach is not used to Filipino street food, you may have a problem. Just try going to restaurants like Gerry's Grill, Yakimix (Japanese food), Kamay Kainan, etc. There's this café I saw on tv: 14 Four Café and they said it was a good place but never been there. You should try it, it's in Taytay.
Um, go to Mall of Asia, Bonifacio Global City, Resorts World Manila, Enchanted Kingdom (amusement park).
Or you can go someplace out of Manila. Like Tagaytay for buko pie, Taal Volcano and other attractions. Or go to Baguio (it's really cold there). Or Subic, Boracay or Palawan. if you like beaches and what not.
Have fun in the Philippines!
I'm a Filipino.