Simplify the following text for a Grade 9 native English-speaking person.
Original: A World Heritage Site , it is home to 20 Eastern Orthodox monasteries and forms a self-governed monastic state within the sovereignty of the Hellenic Republic .
Simplified: It is also commonly used to refer to the Self-governed Monastic State of the Holy Mountain , which is an autonomous part of Greece . There are twenty Eastern Orthodox monasteries inside this state .