This text has a couple of issues. First, "We'd like to encourage websites to use easily, unobtrusive advertising." - This sentence doesn't really make sense, easily what? Using "easy" on its own wouldn't make much sense either, so this line needs to be reworded in a clearer way. Second, "If you still wish to block every ads you can disable this is a few seconds." - This should be "If you still wish to block all ads", not "every ads".We'd like to encourage websites to use easily, unobtrusive advertising. That's why we've established strict guidelines to identify positive ads, which are shown under default settings. If you still wish to block every ads you can disable this is a few seconds.
Of course, this is a relatively minor issue, but probably also a pretty easy thing to fix. I'm not sure if a similar issue exists in Firefox or not. Hope this report is helpful! :)