"The mango is a fruit."
Translation:आम एक फल है।
In English 'the' is definitely (excuse the pun!) used in general statements. Especially when talking about characteristics or properties of a thing, it's pretty frequently used, not really any difference in meaning between 'the is' and ' are'.
If I were talking about a specific mango I can't think of an example where it would be anything other than this/that mango or 'it'.
A famous example that comes to mind is from Kipling's poem The female of the species (one example in the title), and most stanzas end with two examples: 'For the female of the species is more deadly than the male'!