Two-factor Authentication (also called 2FA) is a method of security that introduces a second factor of authentication for account security. Normally you would just have a username and password to log into an online account, but, with 2FA, you would also have a One-time Pin (OTP) provided by an application such as Authy, or Google Authenticator. There are also hardware based 2FA "keys" that you can use which allow you to authenticate via the touch of your finger, such as Yubikey or Google Titan, that can be used as well. One of the earliest forms of 2FA, which you may already be familiar with, is one where the web application will send out a one-time pin via SMS to your phone.
The idea behind 2FA is that you have something you know, which would be your username and password, as well as something that you have, which would be your phone or a hardware key. Most online services, whether it be email or bank accounts, support 2FA, and if they don't, you may want to consider switching to an application or service that does support it.
If you feel you have nothing to worry about, then you may not care to enable two-factor authentication. As long as you take proper precautions and are staying away from shady websites, you probably shouldn't worry. Keep in mind, however, attacks come in many forms, not just in the form of shady websites. Two-factor authentication just gives you an added layer of security on top of whatever security is already provided for you by the web application or service.
In reality, the best way to secure your data and files is to keep them offline, but that would be an inconvenience to most people. Your security is really only as good as your own security practices. My preference is a hardware key; It not only offers a second factor of authentication, but anyone wanting to break into my online accounts would need to physically steal my key in order to do so. So go ahead and pick up a Yubico Security Key for $20 dollars and secure your accounts!
Link: https://amzn.to/2RDzkFJ - Yubico Security Key