modification of a GNU public licenced android app is legal or illegal?

Question

0
I have some doubts about the licenses.
I want to modify a GNU licensed android project and publish on play store.
That project: https://github.com/trebleshot/android
is it legal or illegal?

Answer 1

I often get confused when i try to understand licenseing and copyright systems.
I'm not writing anything here,my information could be wrong, so you have to understand this yourself, I'm leaving a link.
https://en.wikipedia.org/wiki/GNU_General_Public_License#Version_2