Once two people have become acquainted, they think it was their conversation that gave them their information about each other. (Para. 3)
Meaning: Once two people have become familiar with each other, they think it is through talking they get their information about each other.
be/become/get acquainted: to get to know sth./sb.
Be/become/get acquainted is often followed by "with" to introduce an object.
Police said the thieves were obviously well acquainted with the school grounds. 警察说很明显那些贼对校园很熟悉。
She returned to Shanghai, where she became acquainted with many well-known writers. 她回到上海，在这里她结识了许多名作家。