"like a sunbeam" - it is used to give deeper meaning and description to what her face looks like in person so the reader can feel as if they are standing in front of her seeing that face.
Answer:
Various psychological studies have shown that our behavior is influenced by the society we live in and is also shaped by the people we interact with. A child starts to learn how he/she shall behave by looking at other people of the society such as his parents, neighbors, relatives etc.
If a person opposes the norms of a society or behaves in an way which is not common in the society, then he/she is treated in a criticizing way. Such a person will be bullied by every other person and under crucial circumstances may also be told to leave a society.
