Narration means to narrate something and to narrate means to tell something or a story to someone. So narration means to convey or to send some speech to someone. Here we are talking about narration and narration is of two types Direct narration or Direct speech and Indirect narration or Indirect speech. Direct narration is when we convey exact words of speaker to the listener without changing any grammatical or lexical meaning of speech. Indirect speech is when we are the source receiving the speech from the speaker and reproduce it by changing grammatical and lexical sense of the speech and then send it to the listener.
In other words when the speech is delivered directly from speaker to listener without intermediate source it is called Direct Speech and when there is an intermediate source between speaker and listener it is called Indirect Speech.
We find direct and indirect and inverted commas only in written English.
The sentence mentioned above is direct speech because what Ibraham says 'I eat mangoes' is directly passed over to the listener i.e exact words of the speaker are repeated.
The sentence mentioned above is indirect speech because what Ibraham says 'I eat mangoes' is received by us then we pass over this speech to the listener in our own words.