Do you aspire to be an author? Writer? Musician? Do you plan to be in any other business where you will depend on the general public and faithful followers for your income? If so, you need a platform.
What is a platform?
Imagine a politician, standing on a stage (platform), rousing the curious and the devoted into a frenzied roar, after which they go to the polls and put their mark next to his/her name.
This is what we want for ourselves, but instead of voting at the ballot box, we want them to vote by buying our book. Or our music. Or our invention.