Indices of a stock market is a basket of stock that is chosen to represent the general stock market. They are usually chosen based on their market capitalization ( how big the company is), how important the company ( such as banks, telecoms etc.) and other factors.
Here is some values of the major world indices.
As you can see, Singapore has dropped one of the most in the world! So technical speaking, if you have faith in the Singapore economy , you should start investing in it. Because it will most likely bounce back, and gives the highest gain. This can be done by either buying straight into the stocks, or buying Singapore ETF ( exchange traded funds) which tracks the Singapore Index directly.