The SVN url has been changed by SourceForge. In your repository root, or in an individual module, run the command:
svn switch --relocate https://apertium.svn.sourceforge.net/svnroot/apertium/ https://svn.code.sf.net/p/apertium/svn/
Apertium web service
If you want to provide live translation via Apertium for your web site / app / etc. then the easiest way to get started is to use Apertium-apy. Follow Installation to install Apertium and the language pairs you want on your server, then Apertium-apy#Installation to set up APY. Ask us on IRC or the mailing list if you run into trouble.