have (one's) finger on the pulse

Translations
держать руку на пульсе
She really has her finger on the pulse of the fashion industry.
Она действительно держит руку на пульсе индустрии моды.
Definitions
To be acutely aware of the latest trends, developments, or changes in a particular situation, field, or group; to stay well-informed and up-to-date.