The paragraph in a summary is talking about death and overcoming a fear of death.
The answer is:
At age nine, students began learning Latin, which was the language of international affairs.
Relative clauses provide additional information about something that has already been mentioned. In this case, the subordinate relative clause "which was the language of international affairs," makes a further comment about the previously mentioned Latin language.
Confidence is something you gain
And your courage can be strained (just a start)