Here's the correct way to say it:
* Son las cinco de la tarde.
Let me explain:
* Son las cinco: This translates to "It is five."
* de la tarde: This means "of the afternoon" and specifies the time of day.
You can also use these variations:
* Es la una de la tarde: It's one in the afternoon.
* Son las dos de la tarde: It's two in the afternoon.
Let me know if you have more Spanish questions!