What does WordPress mean by they have full rights to content [closed]

This is pretty off-topic — this site is meant for WordPress programming questions — but here’s an answer anyways.

If you’re referring to WordPress.com’s Terms of Service, what you are granting WordPress (actually Automattic, WordPress’s parent corporation) is as follows:

By submitting Content to Automattic for inclusion on your Website, you grant Automattic a world-wide, royalty-free, and non-exclusive license to reproduce, modify, adapt and publish the Content solely for the purpose of displaying, distributing and promoting your blog. If you delete Content, Automattic will use reasonable efforts to remove it from the Website, but you acknowledge that caching or references to the Content may not be made immediately unavailable.

What this means is that, while you retain the copyright to your work, Automattic is allowed to publish it on WordPress.com (which is what you’re signing up for) without paying you or anything like that.

See also: http://tosdr.org/#wordpress-com

Caveat: I am not a lawyer.