If you haven't done it already, you may have noticed prompts to enable two factor authentication for your Google account when signing into their services. Anyone still holding out on doing this will find that it will be enabled whether they like it or not in the next few weeks. This mandatory switch on will apply to all Google accounts including the services they own like Youtube.
For those that are unaware, two factor authentication (sometimes also referred to as multi factor authentication) means that an account cannot be accessed via the password alone. One or more other methods are needed to unlock it. This includes methods such as sending codes via SMS or email, or a notification to allow a login on your mobile device via something like Microsoft Authenticator.
Google have tried lots of things to make accounts more secure. You may have had messages in the past alerting you to logins from a new device or an unusual location. Two factor authentication is the next step of that journey - ensuring the person logging in has access to your mobile device as well as your password. Google suggest they check over one billion password logins a day.
So regardless of the fact that Google is making this mandatory, we would recommend enabling 2FA everywhere you can as soon as you can. Yes, it can be a minor faff to set it up, but when you balance that out with the potential for your data and online presence being compromised, it's a very small price to pay. Hijacking one account can give you a way into other accounts, and with no checks in place, this can lead to identity theft amongst other things. Every account you have 2FA set up on provides a warning system to alert you to someone trying to get into your accounts and investigate before it's too late if necessary.