Meaning of "a window to the world"

Solution 1:

"A window to the world" is used metaphorically. It means that something (reading a book, listening to a news service, viewing a web site) gives you a broader perspective of the world than you would otherwise have. It is something that expands your view, your big picture, your understanding of the world.

An example is: To many people, NPR news is a window to the world.

Here is another example sentence in which reading books [italicized words] is the window:

"Reading provides a window to the world. I can read A Wrinkle in Time and 'tesser' with Meg and Charles Wallace to the utopian Uriel, uncover and nurture a Secret Garden in England, learn what true forgiveness is in a German Hiding Place, immerse myself in teaching with Christy and discover the culture and simple joys of the Appalachia folks."

Solution 2:

OP's example usage is marginally acceptable, but certainly not typical - for two reasons. Firstly, by far the more common preposition is "on"...

...and secondly, "the world" normally means just that - the whole world, not some specific subset such as the world of flora diversity. In the last decade, for example, it's become common to refer to a computer screen (or the Internet accessed through it) as a window on the world. Earlier generations referred to tv, radio, and the press in much the same way - but more metaphorically, "art" has long been described thus (with allusions to life imitates art / art imitates life).

There are thus two "flavours" of meaning to the expression, either or both of which may apply in any given usage. At the more literal level, it may simply allow you to access information / details you already know are "out there" ready to be found. But at the metaphoric level, it's frequently used in the sense of the window offering a whole new perspective on broader issues.