If you are new and want to enable SEO URL’s then you have to follow below point.
System >> Settings then Edit them
Click on Server tab and active SEO URL’s
Create . htaccess file, OpenCart provide default .htaccess file called .htaccess.txt you can rename this file or create new file with below details
Make Apache mod_rewrite turned on.
To use SEO URL’s you need to enable them under your stores server settings
Now start to add your unique SEO keywords for each products and categories.
Now go and enjoy more traffic and happy customers.