Financial Ratios are indicators for the performance of the company as well as good indicators for the near future. They are useful because they can show if the resources that the company uses bring profit and how this ability can be compared with previous years.
Ratios can also show if the company will be able to meet its obligations as they fall due, if its going to be able to pay the interest for the loans that it has etc. All these ratios can be produced quickly and the fact that they offer comparability with previous years and among different companies makes them really good indicators to analyze a company.