Translation:The wind is not very strong.
あまり typically means "not very much" or "not a lot". So, あまりつよくない would be like "not very strong". It essentially softens a negative. I hope this helps. Good luck in your studies.
I had the same answer. Previous uses of あまりin this course have been as "not often".
No, that is not correct English and I don't think any native English speaker would say "the wind is not much strong".