The idiom "Read between the lines" means -

• The idiom "Read between the lines" means - To understand the hidden meaning.

• Read between the lines
English Meaning: to try to understand someone's real feelings or intentions / to understand more than is directly stated
Bangla Meaning: নিগূঢ় অর্থ উদ্ধার করা / মনযোগ দিয়ে পড়া।

Ex. Sentence: Reading between the lines, I think David needs money.
Bangla Meaning: যা বুঝলাম, ডেভিডের আসলে টাকা দরকার।

Source: Website Lecture.