As you have probably figured out already, SEO stands for Search Engine Optimization. SERP means Search Engine Result Pages, ie. the page you see on e.g. Google with the results of what you just searched for. And SE, you guessed it, Search Engine, like Google, Yahoo, Bing and so on.
I’m going to assume that you already have a website or a blog, that you wish to optimize a bit and get some more hits from the Search Engines. Lets start with the first and most important rule.