"What is this?
It is only partial jailbreak. It installs Cydia on special web platform, You only can install some apps an themes from this Cydia, (very limited amount). Normal "untethered" jailbreak runs Cydia on "Cydia Substrate". It is specially designed platform. But Semi jailbreak cannot access to system root of iOS to install "Cydia Substrate".
Therefore it creates special online web Platform to run the Cydia"