SEO stands for search engine optimization and what this means is that you are creating your website in such a format that the search engines will love your website more because you’re following what they are looking for.
With WordPress the default settings for urls (the string of either words or numbers) that come after your domain, called permalinks, isn’t very search engine friendly. The first thing you need to do is to change the permalink settings to a more search engine friendly urls. You can do this simply by going to Settings and then Permalinks.
When you go the permalinks settings, you will have a variety of choices, whether you want to have the date included in the url or whether you want something or nothing else. What I usually do, is to only have the post title showing. However there isn’t an obvious choice for this so you need to be a little creative!
When you click on one of the other options the code will appear, just delete the date code that appears so that only the post name code remains, which will look like this /%postname%/. That’s it! Now instead of seeing your posts as yourdomain.com/?p34 it will show with the search engine friendly urls.
This step should be one of the first things that you do with your WordPress website and certainly before submitting your sitemap to Google and the other search engines as you don’t want your website to be indexed with the non-seo links.