There are a number of generic links you’ll find if you look, eg. Contribute | Ubuntu
@bashing-om has mentioned the Ubuntu Weekly Newsletter, which can be a good place to learn about the community, and if interested, I’ll provide a link to something written about the process - Ubuntu Weekly Newsletter
It mentions how we communicate (IRC), and the different stage of the process. (Do note many teams use different tools, eg. I have Matrix open, IRC open, Telegram… though Matrix is taking over)
For QA testing, I’d suggest reading any of the various posts relating to Testing Weeks, beta and other type releases, eg. Ubuntu 24.10 Testing Week
For documentation, it may depend on where your interest lies (flavor? desktop? server?) but the Documentation Hour comes to mind…
Software development; likewise here I’d explore whatever area interests you; but if you don’t know the various parts of Ubuntu, teams involved etc, the Ubuntu News team maybe a place to learn more about the various parts/teams that make the larger family or entire Ubuntu project.
My next Ubuntu News team task will be tomorrow arvo (it’s Friday night my local time), where I’ll add some summaries to the articles in our current WIP issue.