Translation:Your hair is really long!
I was taught that "zhen" means really and "hen" is very, so in this case "really" is the appropriate choice.
very and really are pretty much synonyms in this case. You won't get very far if you try to do 1 to 1 matching between Chinese symbols and English words words.
If that's the case, the course should be consistent! In other parts of the course the translation of 真 is "very".
When connecting an adjective to a noun, you would use "好" rather than "很", as "很" would mean 'is' rather than 'very'
The audio of part of 长 is pronounced wrong. It should be pronounced as "chang" instead of "zhang"
Audio is still using the wrong pronunciation of 长 as of 2019-03-18. Reported.
Yes I have noticed that this happens throughout this course where a character has two or more different meanings and pronunciations. It seems to be pot luck whether you get the correct pronunciation or not, which is pretty unfortunate when you are trying to learn correct pronunciation as a beginner.
This is such a frequent and damaging shortcoming in the course that I am surprised it is allowed to happen. I guess the program that does the pronunciation doesn't know which is the correct meaning for the given context and the moderators are perhaps not given the ability to specify which pronunciation is correct (or they don't have the time to check every pronunciation).