speak volumes

speak volumes (about / for sth) (to clearly show the nature of something or the feelings of a person) — говорить красноречивее всяких слов; быть весьма многозначительным

Example 1: What you wear speaks volumes about you. (LDOCE)

Example 2: There is a passage early in Augusten Burroughs's harrowing and highly entertaining memoir, Running with Scissors, that speaks volumes about the author. (amazon.com)

Example 3: Gestures speak volumes in the brain.
In the brain, the gift of gab — or at least the gift of knowing what someone’s gabbing about — depends on sight, not just sound. If a listener sees a talker’s lips moving or hands gesturing, certain brain networks pitch in to decode the meaning of what’s being said, a new study suggests.