Wén qǐlái zhēn xiānɡ.

闻起来真香。

It smells good.

Notes:

闻起来(wénqǐlái): to smell

真(zhēn): really

香(xiānɡ): smell good

Example:

A：我带了鲜花给你。

     Wǒ dàile xiānhuā ɡěi nǐ.

     I bring some fresh flowers for you.

B：闻起来真香。

     Wén qǐlái zhēn xiānɡ. 

     It smells good.