When's your birthday?/What day were you born?/What is your date of birth?你的生日是什么时候？你是哪天出生的？你的生日是哪天？
What month were you born?/What year were you born?你是几月份出生的？你是哪年出生的？
How old are you?/What's your age?你多大了？
You look like you're in your twenties./You look twenty-something. 你看起来就像二十来岁的样子
You look young for your age. 你看起来比你实际年龄年轻。

He looks a lot older than his years. 他看起来比实际年龄老一些。

You could pass for twenty five. 不知道的人还以为你才25呢。
I'm pushing fifty. 我快50岁啦。
I'm over forty. 我已经40多岁了。
We're the same age./You're the same age as me. 我们同岁。
If you're old, then I'm ancient. 你要是算老，那我不都成古人了。
What's your sign?你是什么星座的？
I don't pay attention to that stuff. 我从来不注意那些东西。
What's your Chinese astrological sign?你是属什么的？
I was born in the year of the horse. 我是马年出生的。
I'm a dragon. 我属龙。

Conversation:

A: What's your sign?

你是什么星座？

B: I don't know, I don't pay attention to that stuff.

我不知道，我不是很在意这些。

A: What month were you born?

你是几月出生的？

B: I was born in July. 

我是七月出生的。

A: Then you may be a Cancer or a Leo. 

那么，你可能是巨蟹座或者是狮子座。