I think its 7 Frigates for Anti-Submarine Warfare, most likely the Mk13 Launchers and it's Harpoons removed; only the OTO 76mm Cannon and 20mm CIWS will remain.
That and probably a Chinese-made Helo (or a Knighthawk?)
Just to add that the reason why Singapore has such advanced military weaponry not only in the air but on sea as well is because like Sapper said, Singapore is a tiny nation-state.
If the enemy is able to establish a beach head in their territory, it's game over for them... so that's why they...