the sound of a person's foot hitting the ground as they walk

I heard echoing footfalls in the corridor. 我听到走廊里响起了脚步声。

the number of people who go into a shop or business in a particular period of time

Footfall is an important indicator of how successful a company's advertising is at bringing people into its shops. 客流量是说明一家公司在做广告吸引顾客方面有多成功的重要指标。