This is not a script, this is a LDAP filter which means :
Retrieve the entries which are of the type
which possess these attributes populated :
If you want to retrieve the groups which these users are member of, configure on the tool that you want to also retrieve the attribute
memberOf from the users entries filtered.
As stated in the Subject of the question, if you want to know the members of the group
MyGroupName, retrieve the
member attribute of this group filtered by a LDAP filter, for example, such as :