These are the terms/phrases that users type into Google, and site owners/businesses want to be found for, such as 'web design', 'web design sheffield'.
If you don't have a page on your site where you talk about web design in sheffield, it's unlikely you'll feature in the results for a search for that term. But don't abuse this or you will be punished, Google doesn't like being manipulated.
Your webpages should focus on providing good information that's genuinely useful to users who are performing those searches. Think about why users are searching for a term... what information or answers are they looking for. Fill your site with info like that and Google will reward you by sending users to you.
