Just a force tha makes something spin because it (the ‘line of action of the force’ in posh terms) doesn’t pass through the central axis.
A moment is what you do whenever you twist or spin something. You apply an off-centre force to do that and that is a moment.
Mathematically is is defined as
The most common example when learning this is the uneven weights of children using a see-saw (“teeter-totter” in the US I think) requiring them to sit at different distances from the pivot or fulcrum.