you're Indian?
Yepp
Hindi is the official national language
Oh noooo nonono. This is a large misconception (kinda one that was spread intentionally).
So here's the deal. India is very similar to Europe, in that there are hundreds of little cultures that have had very different histories, very different cultures, very different religious practices, etc. At no point in history was India (the current borders) under one state, just like Europe wasn't under one state.
India has 22 official languages, out of which Hindi is the most spoken one (largely in northern India in the basin of the Ganga).
Hindu nationalists have this idea that India needs to be a nation state to protect itself from foreign threats. "A very important step towards that is by having one language that is spoken by all. English can't be that language cuz it belongs to the colonizers. Hindi however, is Indian. Hence, all Indians must speak it."
The problem however, is that those that don't speak Hindi don't want Hindi imposed on them. According to them, English is a perfectly fine bridge language. South Indians generally hold this position. Their languages are very very different from Hindi. Even their scripts are different (like how English and Japanese have different scripts).
Lemme explain this by giving an example of Europe. Imagine Britain colonizes all of mainland Europe. Europe has never been united before. However, to defeat the British, Europe unites for the first time. They drive the British out, and establish their own state.
Now, a group of Catholic Christian nationalists believe that Europe must become more united to fight against such threats. They want all Europeans to speak one language. This language turns out to be German. State institutions across Europe start making their employees only talk in German. Understandably, the French are pissed with this.
That's kinda what's happening in India right now. Many (especially south Indians) are pretty mad about this and are resisting.
I have not heard of Marathi
It's the language spoken in the state of Maharashtra (whose capital is Mumbai).
83 million people speak it natively, while 16 million speak it as a second language. It shares the same script with Hindi. So if you know Marathi, it's kinda easy to learn Hindi and vice versa. There are many common words and stuff. I think a huge majority of Marathi folk can speak an ok amount of Hindi today (largely because of internal immigration from North India to cities in Maharashtra and the aforementioned "Hindi imposition").