Once you reach level 4, you will get the chance to unlock chat. You need to accept the terms and need to be 13 years old or older before you can unlock Messages.

You can find Pockies at the Town Center. You can tap on them and pick "Message" and start chatting. 

If you block someone, you'll no longer receive any messages or notifications from that person. The messages you send and receive are inspected on a regular basis in order to ensure all players can enjoy Pockieland. If a message doesn't comply with our Terms of Service or if it breaks any laws, the message will be deleted and the player will be banned permanently.