That saying obviously applies to women too, so please don't call the PC Police on me. Just like castles of old, our homes can use the same principles of "hardening" to guard us and our loved ones.
A castle or fortification provided the resident or residents with a certain amount of security. They had features like a moat, walls, drawbridge and armed guards. We probably cannot have the same exact arrangements in our place, but we can get pretty close.
Our homes can have exterior security in the form of fencing, walls, or even shrubs and bushes to act as a physical barrier. This can cause the bad guy to pick an easier target. The drawbridge is probably not a option, but exterior lighting with motion detectors are. Those act as a psychological deterrent. The castle usually had a garrison of soldiers. Today that would probably be a logistical nightmare unless you are wealthy, but a dog and/or alarm system is not. Those can act as an early warning system to the most vital layer, your family. If properly trained and equipped, you and your family can be deadly to any invading force. With the right game plan and tools, you can thwart the mightiest invaders.
The idea is to create layers of security that interlock in order to prevent your castle from being overrun. The more layers the more secure. What are your layers? Stay Safe.