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. 警察說很明顯那些賊對校園很熟悉。
She returned to Shanghai, where she became acquainted with many well-known writers. 她回到上海，在這里她結識了許多名作家。