S4C
Welsh Television - the only Welsh language TV channel in the world!
If you are outside the UK, there are still many programmes that you can watch, and there are links to other content (YouTube, Instagram etc)
Y Pod
Podcasts in Welsh. Whatever you like, there's a good chance that you'll find something interesting here.
Listen to something you don't understand at all (you'll get used to the rhythms and sounds of different Welsh-speakers), or adopt a podcast so that you really get to know individual speakers. It's up to you!
Welsh music on Fandom
Welsh music videos with Welsh lyrics and English translations.
It's a Wiki site, so if you have a song you'd like to add, or would like one added, you just need to register to take part.
So useful, I don't know if this is a resource, or entertainment!