When you are fluent in a language you know when one word stops and the next one starts.
When you’re learning a new language you don’t. It’s more like a river of sound flowing past your brain with occasional islands of words which you understand.
It’s difficult for people who speak only one language to understand what this is like, and why it’s so difficult for foreigners to comprehend what they’re hearing, but this might help.
It’s Prisencolinensinainciusol a song by Adriano Celentano, an Italian, who’s singing what English sounds like to him – but it’s not really English, it’s gibberish.
Just between you and me, English is my first language and I find a lot of what passes for songs in a lot of modern music, just as incomprehensible as this one.
The song starts at about 1:40.