"Men eat three bananas."
Translation:आदमी तीन केले खाते हैं।
है (hai) is used for all third-person singular subjects as well as तू (the very informal form of 'you')
Eg: वह आदमी केला खाता है - That man eats bananas
तू खेला खाता है - You eat bananas (addressed to very close friends and family)
हैं is used for all third person plural subjects, हम ('we') as well as आप (the formal form of 'you')
Eg: वे आदमी केला खाते हैं - Those men eat bananas
हम केला खाते हैं - We eat bananas
आप केला खाते हैं - You eat bananas (addressed to people older than you, in a position of authority, those you want to be formal with and most strangers)
हो is only used when the subject is तुम (the form of 'you' that's intermediate in formality).
Eg: तुम केला खाते हो - You eat bananas (addressed to people of the same age as you or younger and certain other people you are close to)
हूँ is only used when the subject is मैं (I).
Eg: मैं केला खाता हूँ - I eat bananas