The best language for business or eCommerce websites targeting the majority of the population in Singapore is English. This is because English is the primary language used in business, education, and government and is widely spoken and understood by Singaporeans of all ethnicities. In addition, Singapore has a large expat community, and English is often used as the common language between locals and foreigners. While it is essential to provide options for other languages, having an English website would be the most effective way to reach most of the population and ensure maximum accessibility and engagement with your target audience.