口が軽い
1
indiscreto;suelto de lengua;ligero de lengua;locuaz
1
having a loose tongue;being talkative;speaking without thinking;being unable to keep a secret
あいつは口が軽いからこのことは言わない方がいい。
Don't tell him. He's got a loose tongue.
Other forms
口がかるい 【くちがかるい】