But does this mean you can modify it and sell it for profits like t-shirt or whatever?
Its CC0 public domain, thats pretty much do what you want:
Dedicator recognizes that, once placed in the public domain, the Work may be freely reproduced, distributed, transmitted, used, modified, built upon, or otherwise exploited by anyone for any purpose, commercial or non-commercial, and in any way, including by methods that have not yet been invented or conceived.