Each bot has a unique token that can be used to control your bot. To get your bot token you must have already created a bot from @BotFather before.
Don't know what is Telegram Bot Father?? Learn more.
Steps to retrieve your bot token
Search for @BotFather and start a new conversation.
It should be verified with the tick icon from the Official telegram.
Send this command /token and you will receive your bot token.