Renesmee can show people the events that have happened in her life, her memories, almost as though showing them a movie of her thoughts. In order to do this she has to be touching them. She touches people's faces in order to share her thoughts. On page 445-446 (Chapter 22), Renesmee first plays her "memory movie" for Bella. Renesmee's gift is related but a bit different from Edwards -- Edward reads minds, but Renesmee can show others her mind. She also has a power in which she can break through Bella's shield, as she comes from and is a part of Bella. She has an innate ability to win people over, it is theorized that Renesmee's power is the opposite of Bella's, while Bella can keep people out with her shield, Renesmee can break through shields (whether physical or emotional).
This is a mix between Edward and Bella's powers. Renesmee can show people in her thoughts by touching someone else. She can show her mind to other people and she does this more often than talking to others.
Renesmee's ability is like the combination of both Edward's and Bella's talents. Renesmee has the ability to show anyone her thoughts in picture form just them letting her touch them. As was seen in Breaking Dawn when she was to help convey to the guests that she was indeed half human. Edward even says she likes to communicate that way instead of using actually talking. She can not read minds but she can show her mind to others.
she can show people what she is thinking by touch. example: if she was talking about a type of car that she has seen and no one knew what kind she was talking about she could touch them and show them that car.