Be no mean…
Definition 1 of 1
Pro Tip 1/3Impressive Skill
Indicates a high level of ability or a noteworthy achievement. 
She's no mean guitarist, her solos are amazing.
Pro Tip 2/3Subtle Praise
A way to express admiration subtly, without direct compliments. 
Managing to fix that complex issue was no mean feat.
Pro Tip 3/3Understatement
Often used to modestly understate one's abilities or an accomplishment. 
Winning that award was no mean feat.