Your WordPress Sitename and Tagline can be used in various places around your WordPress website, but most visibly in your browser window and browser tab.
You sitename is usually set by the user on installation. Some 1-click installers may set a default name for this. By default your site tagline will be set to “WordPress Blog”. It is not uncommon for these settings to be set to the defaults on setup and overlooked on site launch.
Luckliy, changing these is very straightforward.