The simplest method is to add your website description directly to your logo as image.
If you feel confident as developer you can tweak header-extensions.php file which is located in theme folder - library - structure. You will see two function one with logo and one with title as text. You should merge them into one function that does it all. It is matter of copy/paste.
Another solution is just to use forum search to find that this question was answered several times already:
https://colorlibsupport.com/t/add-3-line-text-next-to-the-logo/
https://colorlibsupport.com/t/how-to-add-tag-linedescription-under-header-logo/
https://colorlibsupport.com/t/logo-and-title-next-to-each-other-in-travelify-theme/