What does it mean exactly?
Now that China has paused to reflect and reset, and despite the problems facing Arjun, India is in fact the world’s fastestgrowing big economy. Its GDP, the nation’s income, rose by 7 per cent in 2017, although the usual caveats about separating spin from facts in national statistics apply, especially in a country as spread out as India.
Spin is a term often used in politics to refer to manipulation of information:
In public relations and politics, spin is a form of propaganda, achieved through knowingly providing a biased interpretation of an event or campaigning to persuade public opinion in favor or against some organization or public figure. While traditional public relations and advertising may also rely on altering the presentation of the facts, "spin" often implies the use of disingenuous, deceptive, and highly manipulative tactics.
(Wikipedia)
So separating spin from facts in economic data, especially from developing countries such as India, means that you need to be careful about economic statistics which, in those contexts, can be easily manipulated to present a different, usually better, view on economic growth.
A fact is something actual, real whereas spin, according to The Free Dictionary can mean
(informal), definition #23: the practice of presenting news or information in a way that creates a favourable impression
This said, the information presented in national statistics may not be as accurate as described.
NOUN
3 The presentation of information in a particular way; a slant, especially a favourable one.
‘he tried to put a positive spin on the president's campaign’
‘he was sick and tired of the Government's control freakery and spin’
