Here's an excerpt from google analystics:
Avg. Server Connection Time (sec): 0.12 The average amount of time (in seconds) spent in establishing TCP connection for this page.
Avg. Server Response Time (sec): 0.80 The average amount of time (in seconds) your server takes to respond to a user request, including the network time from user’s location to your server.
Avg. Page Load Time (sec): 7.85 Avg. Page Load Time is the average amount of time (in seconds) it takes for pages from the sample set to load, from initiation of the pageview (e.g. click a page link) to load completion in the browser. If you see zero (0) as a value, please refer to the Site Speed article.
Avg. Page Download Time (sec): 2.08 The average amount of time (in seconds) to download this page.
For example, my site is like this:
1.You can read more info in the following link for how to use google analytics site speed http://support.google.com/analytics/bin/answer.py?hl=en-us&topic=1120718&answer=1205784
2.If you want to break down your site's loading time by digging resources like js/css/html/cgi/php ones, firebug is your friend. You can refer to the following two links for how to use firebug: