The phrase "brilliant acting" means that an actor or actress has performed exceptionally well and skillfully in a role, impressing and captivating the audience. Full definition
Brilliant acting all around, nearly, and wonderful staging. (metacritic.com)
The movie has some of the best comic sequences with brilliant acting by Streep and Steve as they smoke dope and drive to a family date, which is a must - see for everyone who likes class comedy. (timeout.com)
It's a good story and filled with brilliant acting from John Hurt as well as Anthony Hopkins. (gmanreviews.com)