I
noun
BAD : Every woman is entitled to a maternity leave.
GOOD : Every woman is entitled to maternity leave.
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leave (= a number of days, weeks or months when someone does not have to do their usual job) is usually an uncountable noun: 'Government officers get six weeks' annual leave.' 'First she was on sick leave, then she took study leave, and now she's applied for maternity leave!'
II
verb
1
BAD : I leave from Bilbao on 12th June.
GOOD : I leave Bilbao on 12th June.
BAD : I left from the shop without buying anything.
GOOD : I left the shop without buying anything.
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leave somewhere (usually WITHOUT from ): 'If I leave the office at six, I'm home by ten to seven.'
Use leave from only when you want to refer to the place where a journey, trip, excursion etc begins: 'The coach will be leaving from in front of the hotel at six o'clock sharp.'
2
BAD : Ken's aunt left to New York on 17th April.
GOOD : Ken's aunt left for New York on 17th April.
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leave (somewhere) for somewhere else (NOT to ): 'She'll be leaving for London on the nine o'clock train.'