英语太难了,学得我头大。
I just don't want to use "head exploding" which scares me.
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Sign up to join this community頭大 figuratively means to be distressed/overwhelmed/worried. In English, the equivalent word is the figurative headache.
英語太難了,學得我頭大
English is too difficult; studying it is (too overwhelming) / (giving me a headache)
头大 just means 'head is big' as in "头大没脑" (big head but no brain)
The common phrase is 头也大了 or 头都大了 . e.g. "英语太难了,学得我头也大了。"
The English expression "make my head spin" is a good counterpart of it
You can also simply say "my brain hurt"