This overused term means organizing and setting up a website for the search engines to not only find it, but find it useful. There are many things included in SEO, from back links to how your website is set up. The speed of a website is very important because very few people let a website load over 5 seconds, before they click back.
There is also the need for good optimized content, so that the search words you want to be targeted are relevant. If your website is about growing roses, there is enough and efficient information about growing roses. This will make your site easier to find and locate.
Search Engine Optimization is a slow process, however. It takes time to create backlinks and time to create good content. Anyone telling you they can get you to page 1 of Google, fast, is lying. If you have a small, very specialized niche, it may be possible within a month, but everything else can take 3 months or longer, especially if it is a highly competitive field.