Unless you are a citizen of a country that doesn't need a visa to visit Singapore, you will need a Singapore visit visa. The Singapore government has made it easy and quick to get a Singapore visa online. You can apply from the comfort of your own home.
The cost of a tourist or business visa for Singapore is Rs.2000/-.
It depends on the situation of each foreigner in question. With a visa, though, foreigners can stay in Singapore for up to 30 days. But if they want to stay longer, they must apply for a long-term visa.