Footfall means the sound of a footstep, especially when you can hear someone walking nearby. When you're reading quietly in your room and hear the footfall of your parent approaching down the hallway, you know someone's coming even before they knock on your door.

The word often appears in stories to create suspense or atmosphere. A character might hear mysterious footfalls in an empty house, or a guard might listen for the footfall of approaching strangers. Writers use it because it sounds more vivid and precise than just saying “footsteps.”

The word can also mean the number of people visiting a place, especially in business. Store owners track their footfall to see how many customers come through their doors each day. A shopping mall might advertise high footfall to attract new stores, meaning lots of potential customers walk through. After a new playground opens, the park might see increased footfall as more families discover it.

Notice that in this second meaning, you're still counting feet, just in a different way: instead of listening to individual steps, you're counting all the people walking into a space.