The svn checkout (or svn co for short) command can be used to check out files from one of your Subversion repositories. For example, let's say http://example.com/svn/repo/testing/ is a repository of files being version controlled by Subversion. You can check out the repository. This creates a working copy of the repository on your local system.
svn co http://example.com/svn/repo/testing/ /tmp
You can then modify the files locally. Once you are ready to commit the updated file back into the Subversion repository, you would check in the file.