The HT in htaccess stands for hyper text and the htaccess file in WordPress controls access for configuration of different directories on an Apache server without the need for root access.
Your htaccess file is generally writable so if you want to change your permalinks for example, WordPress will check permissions in your htaccess file automatically.
You'll need to be using an Apache web server with mod_rewrite installed which is normally standard with most good WordPress hosts.
Lets take a look at what a normal .htaccess file looks like. Simply login to your web hosts cPanel > Files > File Manager. Its here you'll see your htaccess file located in the top level public_html which is also called your web root.
What is a .htaccess file & why is it needed?
Your htaccess file offers a way to make changes (configuration) to your different directories (folders) without having to make them at the server level which would require direct root access.
This is generally reserved for VPS & Dedicated server users rather than shared hosting clients as allowing 6000 shared hosting users root access to one server allows them root access to every sites files and databases hosted on that server.
Using .htaccess is generally negative for your sites performance as your server needs to check every level of your file system every time a page loads. This is one of the many reasons root access to your server via VPS or dedicated is a bonus as you don't need a .htaccess file.
If you need to make any changes to your .htaccess file i suggest you contact your web host as they deal with server issues daily. Otherwise its better you don't play around with .htaccess file.