drush aliases allow you to run a drush commands on your local server but actually execute the command on a remote server.
One can create aliases in a folder that drush recognizes, mostly inside the .drush folder for Linux Based Systems. For a mysite example, we can create a file called as mysite.aliases.drushrc.php inside the .drush folder (Or any folder which Drush goes through before executing). All aliases in a site can also be combined in a single file called as aliases.drushrc.php
Example data that can be added to mysite.aliases.drushrc.php