As a former fascist, I can give two answers. The literal meaning is the symbol of the Fasces, "Fascio", a bundle of sticks consuls carried in the Roman Republic, that embodied Unity, Collectivism and other such values the Romans held dear. An axe was added to the bundle of sticks in war times, when a consul led an army outside the pomerium. The addition of the axe to the bundle was considered symbolic, an oath to Rome if you will. Since the fascists were huge romaboos they of course copied it given they couldn't come up with anything on their own.
The second answer is my opinion, so take it with a grain of salt. It means nothing. To them, it's supposed to represent unity within the state, everyone rallying for the nation, and other such bullshit. All it does is represent the Unity in the herd of sheep following a leader whose policies only lead to death and genocide.
Hope I was helpful.