As Singaporean you have the privilege to buy EC direct from developer. EC is a subsidized private condominium where you got to buy at lower price compare to the surrounding private condo.
Because it is subsidized, government implemented few rules in which EC buyers need to follow such as there must be at least one Singapore Citizen combine with another Singapore Citizen or SPR.
And they must form family nucleus in either: public scheme, fiance/fiancee scheme, orphan scheme, or joing single scheme. More on the combination of the family nucleus, CPF Housing Grant, and other details you click on Eligibility to buy EC