That's a web server component that should automatically be present on all modern web servers.
How to test if it is availabe:
1. Create a .txt file "mod_rewrite.txt" in the root folder (document root) of your website with this content:
mod_rewrite is activated.
2. If a .htaccess file already exists in the root folder, rename the file so that it is not unintentionally changed by the test in the following step.
3. Create an .htaccess file in the root folder (document root) of your website with this content:
RewriteEngine On
RewriteRule ^.*$ mod_rewrite.txt
4. Open the website in the browser. If mod_rewrite is activated - which is the case by default in all webspace accounts - you will see the following output:
mod_rewrite is activated.
5. Delete your .htaccess file and rename the backup created in step (2.) back to .htaccess.