That's good for you.
A: I've decided to go back to school for some training in programing.
A: 我决定再回学校进修程序设计。
B: Good for you. When would you like to start?
B: 不错啊! 打算何时开始?
"good for you" 是某人(将要或已经)做一件对他自己有益的事时, 所表示“认同”的话。
例如一个不爱运动的人告诉你, 他要开始每天运动了, 你就可以回答"Good for you!"。
怎么样?明白了吗?