A Microsoft Account is similar to any other computer account: it is a set of credentials - a username and a password. What's different about it is that entitles the account holder to access certain resources that reside on Microsoft's servers that would otherwise be unavailable.
When you first use Windows 10, it will ask you to create a Microsoft account. If you create such an account, the expectation is that you will thereafter normally use that account to log into your Windows 10 PC. This is because Windows 10, if it is to be used to its fullest capabilities, is a hybrid operating system, which expects to interact constantly with Microsoft's servers to make use of data and resources maintained at Microsoft. This interaction supports such capabilities as enhanced browsing security, automatic updating, synchronization with other devices (including Android phones and iPhones), and many other features.
You can also create local accounts on the same computer. Local accounts will not interact so routinely with Microsoft's servers, but will permit you to perform most actions you would want to perform: browse the net, create documents, run backups, get email, and so on. You will not be able to make full use of such capabilities as Cortana, Windows Hello, and several kinds of anti-malware capabilities, as well as many other features, but basic computing facilities will still be available.
Any accounts, of whatever kind, will be listed under the Settings > Accounts page.
Creating a Microsoft Account
There are, again, several ways to do this:
Do I Need a Microsoft Account?
It is probably more convenient for most people to create a Microsoft account. For example, without a Microsoft account, as explained above, you will find some features difficult or impossible to use, as well as missing out on some enhanced security features.
One choice might be to create a Microsoft account which has administrative capabilities, which can be used to log on to the computer when administrative tasks need to be performed, and use a local account for everyday work, play, and browsing.