LocaMon is class which allow you to simple convert time into localized names. For example month numbers into names.
$locaMon = new LocaMon();
$monthNumber = 3;
$timestamp = mktime(0,0,0,$monthNumber);
$locaMon
->setLocale('pl_PL')
->setFormat('LLLL')
->setData($timestamp);
echo $locaMon->getResult(); // marzec
About format: datetime