He means that India is a large (as in population, which is an indicator of possible industrial and economic power, military, etc) country that is a democratic country as well. That's important because democratic countries tend to align together, since public opinion matters and public opinion generally favours peace, especially against other countries that also generally want peace. So, the importance of India is that it could act as a counterweight to China in Asia. China obviously is an economic giant, but as a military power it is largely regional and has little ability to project force. A powerful India limits its abilities in Asia.
