The cup is using Japanese letters that look somewhat like English letters to spell "Soul of Coffee". The comment is how those letters are read in Japanese.
All us former or present weebs that once learned Hiragana, Katakana, maybe 5 words and phrases, and basically nothing else, understand. (And the people actually speaking Japanese, too)
Anime is a really good tool if it's something you're into. Just have a dictionary pulled up if you hear words you don't know. I've been studying Japanese for ~5 years now and the first 2 years were mostly just listening to anime and doing kanji flashcards. You can get surprisingly far with just anime, but yeah it can't be the only tool. 勉強は頑張ってください 🙂
Oh, back then I totally also used.... some websites I found on google. And, uhm.... I think I remember printing out a torrented professional Japanese handbook, making a fancy folder to put it in and then.... never actually using it. :D
As you can see, teenage/young adult me was very realistic and very committed!
Reminds me of probably the most pretentious thing I ever did: as a teenager in the late 90s, I tried to learn Russian in order to read Tolstoy and Dostoyevsky in the original 😆