Basically any equipment, any physical things that one needs to work will come under physical resources.
Wether you have a small home business, a small startup or a successful business. You obviously need all the appropriate equipments and raw materials to do you job.
Let's take an example of a factory, you need all the raw materials, the machines, the control systems and safety equipment. Similarly every company kr business needs physical resources to do stuff.
You may have very good funding and really good human resources but without the equipment, where will the people work? What eill they make?
Thus it's immensly important for a startup to acquire and maintain physical resources and ensure quality of them