SEO is the acronym for search engine optimization, which just simply means improving your websites visibility to search engines like Google so you show up. For example, if you’re a family photographer in the Chicago area, good SEO simply means when someone searches “Chicago family photographer”, you show up as the first result or on the first page.
And yes, you need SEO.
SEO, once you really look into it, is fairly simple to implement. Hiring an SEO expert would 345324% be faster, but if you’re just starting out, that may not be an option. Sometimes web designers will offer SEO in their services (I offer basic SEO integration), but more often than not they leave it up to you.
If you’re wondering where to get started, here’s a good list of websites that help with keyword research.