"He/She looks a lot like you, you know? Haven't they told you?"
Here's a breakdown:
* Se parece bastante contigo: "He/She looks a lot like you"
* tu sabes: "you know" (this is used to emphasize something)
* o no te lo an dicho?: "Haven't they told you?"
The sentence suggests that the person being discussed resembles the person being addressed. The speaker is surprised that the other person hasn't noticed this resemblance.