it is so you can include characters in the text which would normally cause problems, i.e. in a csv you can't include a , in a field - but if you use the text qualifier (normally " but can be anything) - any text between the two "'s is allowed:
To save this in a csv: Hello, My Name is...
would result with: Hello, My Name Name is... - which is two fields
using a text qualifier : "Hello, My Name is..." - is just one field
Ed