不能只看外表英语

It's good to learn one person by learning his(her）heart instead of outside.

人不可貌相，海水不可斗量 有人译为： A man can not be known by his look, nor can the ocean be measured by a dipper. 这样的译法只是直译，如果能够稍加修改，老外就能了解： A man can not be judged by his appearance, nor can the water in the sea be measured by a bucket. 不过，老外通常的说法是这样的： We can not judge a person by appearance only. 或 You can not judge a book by its cover. (意思是：一本书的好坏取决于它的内容，而不是它的封面装帧的漂亮与否。)

See a person can not only see the appearance and to see his heart

Don't just look at the word it means.

不知道你具体要用在什么地方。但是这一句是说，内在很重要：It's what's inside that counts.