Union Government
(1) There shall be a Council of Ministers with the Prime Minister at the head to aid and advise the President, who shall, in the exercise of his functions, act in accordance with such advice: Provided that the President may require the Council of Ministers to reconsider such advice, either generally or otherwise, and the President shall act in accordance with the advice tendered after such reconsideration. (2) The question whether any, and if so what, advice was tendered by Ministers to the President shall not be inquired into in any court.
This is one of the most important articles for understanding how India is actually governed: real executive decision-making power lies with the elected Council of Ministers headed by the Prime Minister, not with the President personally. The President must act on their advice (though the President can ask them to reconsider once) - making the President's role largely ceremonial rather than a personal decision-maker, unlike, say, the US President.
This is why the Prime Minister and Cabinet, not the President, are understood to be the real decision-makers on government policy - the President's formal assent is constitutionally required for most actions, but the substance of the decision comes from the elected Council of Ministers.