What is the source? The "Browse any website" claim implies that you're translating on the fly and then I learn by translating back to English. Is this the case?
All content is native content in the foreign language you are learning. Suppose you are learning Spanish - we'll show you a feed of popular news articles originally written in Spanish so you can practice by reading those. There is machine translation built in for words or sentences that you might need help with. We'll even automatically create flashcards for you for words you look up, to help you review with spaced repetition later.
When we say "browse any website" we mean that Flowlingo can be used as a general purpose browser - you can navigate to any website in Spanish and use the same learning tools to practice!
This is also implied by their suggestion of "learn the culture surrounding a language with local trending news."