Working hours cannot exceed eight hours in any 24 or an average of 40 hours in an average five-day working week in a reference period applied by the employer of not more than four months (however there are some exceptions e.g. in case of so-called 24-hour shift work).

Overtime in Poland cannot exceed 150 hours in any one calendar year for each worker (although some exceptions apply). Weekly working hours plus overtime cannot exceed an average of 48 hours in the reference to period applied by the employer.

All employees are entitled to an annual unbroken paid vacation.  An employee just starting a work attains the right, in the calendar year in which he starts work, to vacation with every month that passes. Every month he is entitled to 1/12 of the total vacation to which he is entitled after one year of work. An employee gains the right to the next vacation in each subsequent calendar year.

An annual vacation entitlement for an employee working less than 10 years is 20 days (26 days if over 10 years).

Beside paid leave, Polish workers can enjoy many national and public holidays (non-working days):

• 1st January, New Year's Day Sunday and Monday of Easter (movable)
• 1st May, State Holiday 3rd May, Constitution Day
• 9th Thursday after Easter, Corpus Christi (church holiday)
• 15th August, Assumption of the Blessed Virgin Mary
• 1st November, All Saint's Day
• 11th November, Independence Day
• 25th & 26th December, Christmas

Source:
http://www.paiz.gov.pl/
http://en.wikipedia.org/wiki/Holidays_in_Poland