"I drink tea."
Translation:मैं चाय पीती हूँ।
Hai/hoon (है/हूं) are the conjugations of the verb hona which means "to be".
Hai (है) is for third person singular, the English equivalent being "is". Hoon (हूं) is for first person, the English equivalent being "am".
They are necessary in the sentence to show this is the present simple tense and nothing else.
Main piti hoon (मैं पीती हूं). I drink, in the present simple.
Vo khaata hai (वह खाता है). He eats, in the present simple.
I feel like the course just made a big jump, like I don't know all these words in writing yet and have to guess from the other words they are with. If it was spoken as well it would be better... But at this point many of the word make no sense to me and I just have to guess :/