Can I use Charles Proxy to monitor traffic for an online android game like PUBG. If yes then what all information can I get from this? Can I use this to monitor the packets which are sent to the game server while playing the game and get the information like the ping I am getting while playing the game?
Online games usually use UDP (and sometimes also raw TCP and/or HTTP(s)) traffic, but Charles is a web proxy that captures only HTTP and HTTPs traffic. Therefore you will only see a small part of the traffic.
The in-game ping usually bases on the UDP traffic, therefore using a pry will also not help you to get your ping time. AFAIK PUBG has a built-in ping time viewer that can be enabled in-game.