I have a Unix timestamp and would like to get the name of the preceding month e. g. "Ferbruary"
$date = 1489842000;
$lastMonth = getLastMonth($date); //Ferbruary
strtotime is your friend here:
echo Date('F', strtotime($date . " last month"));
For anyone that wants this fully dynamic, to always display last month's name, the code would be:
$currentMonth = date('F');
echo Date('F', strtotime($currentMonth . " last month"));