What does HTML URL and http means?

HTML stands for "hypertext markup language" which is the language used to code web pages for display in an internet browser.

URL is an acronym that stands for "universal resource locator." This refers to an internet address, like www.answers.com. It give information for obtaining a resource. (In the prior case, go to the .com servers, find the answers servers, and then ask for the document located at the www subdomain.)

HTTP is also an acronym that refers to the "hypertext transfer protocol." HTTP is a standardized set of rules used to transfer HTML documents (and a few other things, like images) across the web.

All three are related. The URL tells the browser where to find a resource. The resource is most often an HTML page. And HTTP is most often used to retrieve the HTML document located by the URL.