Only 10 percent of India’s 1.3 billion people know English. Yet most of the country’s e-commerce services have been offered only in English, closing off online shopping to the vast majority of people here. Now Amazon is aiming to break through that language barrier. The e-commerce giant offered a hearty “namaste” to this country’s half a billion Hindi speakers by making its local website and apps available in India’s most popular language. Users of the India site or app will be able to choose Hindi as their preferred language, much as American users can choose Spanish. Amazon’s expansion into Hindi — its first foray into an Indian language, even as other companies have tried that strategy and pulled back — is vital to the company’s ambition of making India its next big market. Amazon is already the No. 2 player in India’s $33 billion e-commerce market and it has about 150 million registered users here. But as it seeks to reach the country’s farthest regions and appeal to less-educated customers in the world’s fastest-growing pool of internet users, it has found that English is not enough. “The next 100 million customers will have to be in the vernacular language,” said Kishore Thota, director of the customer experience and marketing for Amazon India.