Choose your team, team Valor, Instinct or Mystic and you will access the global map. In the map you will have a geochat where you can communicate with all the trainers from Pokémon Go. You have also a private chat where you can talk with the players on your team.
The read state permission is used for a unique identification of your mobile phone and create an account in Geochat.
The location permissions are used for send a message in your location.