I am confused about why python needs cursor object. I know jdbc and there the database connection is quite intuitive but in python I am confused with cursor object. Also I am doubtful about what is the difference between cursor.close() and connection.close() function in terms of resource release.
The cursor paradigm is not specific to Python but are a frequent data structure in databases themselves.
Depending on the underlying implementation it may be possible to generate several cursors sharing the same connection to a database. Closing the cursor should free resources associated to the query, including any results never fetched from the DB (or fetched but not used) but would not eliminate the connection to the database itself so you would be able to get a new cursor on the same database without the need to authenticate again.