Essentially, Telegram's two-step verification enables users to set a password required every time they log into their account from a new device, apart from the code sent to users via SMS.
What happens if you turn off 2-step verification?
Your account is more secure when you need a password and a verification code to sign in. If you remove this extra layer of security, you will only be asked for a password when you sign in. It might be easier for someone to break into your account.
What does the 2-step verification do?
When you sign in, 2-Step verification helps make sure your personal information stays private, safe and secure. In addition to your password, 2-Step verification adds a quick second step to verify that it's you. 2-Step verification is a proven way to prevent widespread cyberattacks.