How is the underlined gerund used in the sentence? her hobby in the springtime is gardening.

In the sentence: Her hobby in the springtime is gardening.   T

he gerund in the sentence is ‘gardening’.
 
It is used as the subject of the sentence. Gerund are verbs used as subjects in a sentence with the root word added by ‘-ing’. Verbs are simply known as the ‘action’ words – may it be mental, physical or mechanical. When verbs are paired with auxiliaries (helping verbs), they are known as verb phrase. These helping verbs always go first before the actual verb.   

One of the moral truths that is highlighted in the story "The Prisoner Who Wore Glasses" is how people are able to achieve so much more when they work as a group, as opposed to acting individually.

In this story, we learn about a group of prisoners in a South African jail. They are political activists, and enjoy a good degree of freedom. However, this is threatened with the arrival of a new, strict warden. The group, however, is able to fight against this new authority due to the fact that they always operate as a tight group, and that there is rarely any conflict among themselves.

This truth is particularly meaningful in this context, as the prisoners are being punished for their social and political ideas and activism. The prisoners have a deep care and concern for society and they want relations among people to become fairer and more peaceful. However, they also act in accordance to this principle, as they attempt to create peaceful and cooperative relationships both among themselves as well as with the authorities. This is examplified by how the group always replies in unison, or by the fact that the warden joins the prisoners in working at the farm.