Off-Page SEO
This is when search engine optimization is done that is not included on the page that you are working on to build the SEO. Examples of doing this include building backlinks to the page on other websites, Google Ads, TV and Radio Ads that ask you to visit your web page, etc.
On-Page SEO
These are tactics to improve the search engine optimization for your web page that is done on the page itself. Examples of this include content marketing, proper use of LTI, keyword placement, outbound links using the nofollow attribute, etc.
Organic Search
This is used to describe traffic that comes to your website through the use of natural use of using search engines to come to your website instead of through paid searches like Google AdWords.
Orphaned Pages
Orphaned pages are pages of a website that are not linked to any other pages of the website. In SaaS (software as a service) software they are usually detected and brought to your attention as a warning to fix but you may create an orphaned page on purpose as a landing page to try to increase conversions to what you are trying to do on that page.
Outbound Links
These are links on your website that point to another website instead of your own.