A schema is the preconceived framework of cognition that helps us interpret information and react accordingly.
Here, Jack has never been to a funeral before but knows about funerals through other people's experiences. Also, his exposure to movies and TV shows that depict funerals have informed him about funerals. So, he has a fair idea about the cultural and traditional customs that are to be followed when attending a funeral.
Hence, the psychological concept being described here is schemata.
