For a website to rank highly on a search engine under keywords that will bring you business, it must designed in an appropriate manner.  Properly optimising your pages to make them "search engine friendly" will greatly increase your search engine rankings, visitor numbers, and potential earnings from your website.

To put it simply, if your business does "gardening and landscaping" you would like your website to show up in the first few pages of a search engine (e.g. Google) if that term or a similar one is searched.  That is what search engine optimisation is all about.