How to check if a checkbox is checked in pyqt

x = self.folderactive.isChecked()

x will be True or False—a Boolean value.

(It's the brackets at the end that make the difference.)

self.folderactive.isChecked isn't a boolean, it's a method - which, in a boolean context, will always evaluate to True. If you want the state of the checkbox, just invoke the method:

if self.folderactive.isChecked():
    ...
else:
    ...