Generally, interest received from deposits with approved banks and licensed finance companies is not taxable. You may check whether a bank is an approved bank or a licensed finance company on the Monetary Authority of Singapore (MAS) website.
In addition, interest received from your foreign banks is considered as foreign sourced income and not taxable in Singapore (exceptions apply).
Gains derived from the selling of personal investment, such as shares, are generally not taxable as they are regarded as capital gains (unless you are deemed by the IRAS to be in the business of trading in shares). There is generally no capital gains tax in Singapore.
Gains derived from the sale of a property in Singapore are generally not taxable as they are regarded as capital gains (unless you are deemed by the IRAS to be in the business of trading in properties). There is generally no capital gains tax in Singapore.
Any proceeds derived from the sale of an overseas property is considered as foreign sourced and is not taxable in Singapore (exceptions apply).