between dates function in sql

Assuming that the column: pol.date_entered has a data type of: date, and that the actual values in that column include the time of day, then awking00 is correct.  That is, Oracle date columns and variables include a time portion, so when you ask Oracle to return values that are between the dates of: 1-Oct-2005 and 10-Oct-2005, Oracle assumes a time of midnight for both of those dates (since you didn't provide a different time portion) and records that were entered on the 10th, but after midnight (which is probably most or all records for that day) are excluded.  You have to use either the extended date/time format that awking00 provided to include the records for later times on the 10th, or if you think there are no records that have a time value of exactly midnight, you could use:
 
and pol.date_entered BETWEEN To_Date ('01/10/2005', 'dd/mm/yy') AND To_Date ('11/10/2005', 'dd/mm/yy')

That would actually get the records from 1-Oct-2005 (any time of day) through the end of day: 10-Oct-2005.  Be careful with this approach though, since if there any records for exactly midnight on the 11th, they would also be included.

Or you could use two separate conditions instead of "between" like this:
and pol.date_entered >= To_Date ('01/10/2005', 'dd/mm/yy')
AND pol.date_entered < To_Date ('11/10/2005', 'dd/mm/yy')

Note that you have to use ">=" for the minimum date (in case there are records for exactly midnight on that day) and "<" for the date one date beyond the date you want included.