While a direct Hindi dub might not exist, watching the original with subtitles is often considered the best way to experience the true "waves" of Mani Ratnam's vision.
Search for Alaipayuthey on Amazon Prime Video (Tamil with English Subs). You won't regret it.
: Be wary of websites promising a "Hindi Dubbed Full Movie Download." Since an official dub doesn't exist, these are often clickbait or contain malware.
Alaipayuthey (2000) was officially remade in Hindi as (2002), the original Tamil masterpiece is widely available in Hindi-dubbed versions on various streaming platforms. Directed by Mani Ratnam