backlink is simply a link from one website to another.Search engines looks if there is a link on a website of another website means that website trusts content of refring website. So backlink helps in increasing authrority of your website.
bot si the crawler which access the pages of website .
canonical url means a preffered website url, when there are multitple url with similar content.
seo full form is search engine optimization which is used to make rank your website to top in search result.
most important guidelines to do seo of any website 1.Give page name according to property or work or keyword for example about.html ,gallery.html 2.Title name should be used three or four times in page . 3.Keep navigation and description information in header tag. 4.Keep footer credit name as link. 5.Comment your website link on others already ranked site. 6.Add attribute in img tag (most important to rank images) 8.upload sitemap to google search console. 9.Bold keyword in description. 10.Set keyword in first heading first line of first paragraph 11.Key word in conclusion of your post or page. 12.Minimum keyword density should be 1% and maximum 2%, example- for 1000 words 20 keyword. 13.If you want to priorities specific keyword then place that in initial lines of your post or page. 14.