I agree she types accurately, but then ______, she's very slow.

• শূন্যস্থানে সঠিক উত্তর হবে - again.
- Complete Sentence: I agree she types accurately, but then again she's very slow.
- Bangla Meaning: আমি একমত যে সে সঠিকভাবে টাইপ করে, কিন্তু একথাও ঠিক, সে খুব ধীর।

• But then (again)
- English Meaning: Used when you are adding a statement that says almost the opposite of what you have just said
- You use but then or but then again before a remark which slightly contradicts what you have just said/ on the other hand (introducing a contrasting comment).
Bangla Meaning: অন্যদিকে, তবে একথাও ঠিক।

More examples:
- John might be ready to help us, but then again, he might not.
- You feel sorry for him, but then again, it’s hard to like him.

Source:
Cambridge Dictionary,
Oxford Learner's Dictionary,
Longman Dictionary,
Collins Dictionary and Accessible Dictionary by Bangla Academy.