the app teaches symbols and chinese, but how do I know what it is in english?
You don't, you gotta learn those through trial and error. I do wish they'd teach it from the get-go but alas, no such thing - you don't learn how to write Chinese either.
I really recommend using HelloChinese, its interface is straight ripped out of Duolingo's, which makes it better for Duolingo users, and also contains exercises to teach you how to write Chinese characters as well as what they mean.
The above extension on Chrome Desktop will highlight definitions for single words and phrases. It only works on desktop and there's certain exercises where it behaves poorly or fails to trigger like when characters goes grey after successful matches. There are similar extensions but this one supports text to speech which is very helpful.
ALSO MAKE SURE TO SET: Popup delay: 1ms
The default is 0ms which causes the extension to not trigger on some systems.