It expresses the idea that a single glance can convey more meaning and emotion than a long and elaborate explanation. It highlights the power of nonverbal communication, especially in expressing feelings like love, understanding, or sorrow.
Here's a breakdown of the phrase:
* Una mirada: A look, a glance
* Vale: Is worth
* Más: More
* De mil palabras: Than a thousand words
So, it's similar to the English proverb "Actions speak louder than words."