A Terms of Service agreement is optional for your website or mobile app. It's not required by law. It's recommended to have this kind of legal agreement: you can set the rules to which users must agree to in order to use your website, mobile app, SaaS application, etc.
Credit or debit card information to process payments
And many more categories of data that are considered personal
The purpose of this kind of legal agreement is to simply state that you (your company, your app etc.) will collect personal data, and to explain how, which kind of data is collected, and what you will do with this personal information.
The license from WordPress
This license allows you to copy the agreements presented by WordPress.com and adapt it for your website, but you are required to credit WordPress for this agreement (a link back to their website.)
You're also required to release your agreement (with whatever edits you did on top of the original agreement from WordPress) under the same license, the Creative Commons Attribution-ShareAlike 3.0.
Briefly, the Attribution-ShareAlike 3.0 license allows you to:
Share the agreement, meaning: to copy, distribute and transmit the work
Remix the agreement, meaning: to adapt the work
Make commercial use of the work, meaning to use it for a commercial website
But, under these conditions:
Attribution, meaning: you must attribute the work to the right owner (in this case, WordPress.com)
Share Alike, meaning: if you build upon this work, you may distribute the resulting work under the same license, Attribution-ShareAlike 3.0
Copy-paste the Terms of Service from WordPress
You can copy the Terms of Service of WordPress.com, but it's important to keep in mind that their agreement is suitable for their own business needs, their own website functionality, etc.
Your business can be completely different and include a clause from WordPress.com Terms of Service, that doesn't align with your industry, and therefore isn't a good solution.
Remember that a Terms of Service is the contract which binds users to the rules you've set:
A Terms of Service Agreement is a set of regulations which users must agree to follow in order to use a service.
If you're drafting your own Terms of Service, you can copy parts of the agreement presented by WordPress such as the "you agree to become bound by the terms and conditions of this agreement" section:
Please read this Agreement carefully before accessing or using the Website. By accessing or using any part of the website, you agree to become bound by the terms and conditions of this agreement. If you do not agree to all the terms and conditions of this agreement, then you may not access the Website or use any services. If these terms and conditions are considered an offer by Automattic, acceptance is expressly limited to these terms. The Website is available only to individuals who are at least 13 years old.
This Agreement does not transfer from Automattic to you any Automattic or third party intellectual property, and all right, title and interest in and to such property will remain (as between the parties) solely with Automattic.
If you need the Intellectual Property clause in your Terms of Service, this clause above from WordPress.com is a good starting point.
Their Terms of Service can provide with a good basis to start your own agreement.
You can copy most of their sections and clauses if you know that these are going to fit the needs of your website, such as Introduction, Intellectual Property, Termination and so on.
But remember to double-check to make sure that it applies to your own website and your own business needs.
Note that telling users "to frequently check this page for any changes" is no longer recommended. That's called a browsewrap agreement and it's no longer a good best practice to follow.