hi , SEO stands for Search Engine Optimisation. Basically it it teaching you how to rank on top of Google Search Result Pages. Example if you own a website talking about Home Air Purifiers, then you would love your website to appear on the 2st page of Google results page when people search for the keyword"Home Air Purifiers". So it is something worth to learn if you want to be in internet biz.
You can check out my website http://addykho.com and http://www.instantcashinbox.com to find out more about SEO as I will be posting something about SEO soon.