Typically, a simple way to think of an input is anything that costs money. These can be both good and bad things. A simple example would be: if I had a machine that made candy: my inputs would be the energy required to run the machine, the person required to work the machine, and the ingredients I had to put in to make the candy. My outputs might be the candy the machine made and the happiness it gave to people who ate it. A negative output might be that it made people unhealthy.
As an internet company eBay does not have many of the typical inputs of doing business. For example, it does NOT have the cost of physical stores nor does it have the cost of depreciating inventory or any machines. For eBay, some examples of inputs would be it's people such as software engineers, marketing team, and executive staff. All overhead such as office space and the electricity to power its office space would be another example. Other examples could include the physical code behind eBay's software and money used to finance the company, and the data warehouses used to store everything.
Outputs can be thought of as the value a company creates. eBay's outputs are also somewhat atypical. eBay does not create a physical product that they then sell so that makes this a challenging question. You could argue that eBay's store or its platform is an output. All the data it produces as a company is an output and has a lot of value. Since eBay allows people across the world to open up their own store online, you could say it's creating the social good of jobs or entrepreneurship "global employment" through this action (eBay has supported this publicly as well so you could look up more about it on Google). Another output could be eBay stores created by sellers. eBay owns PayPal so if you can think of any related to PayPal you could include those as well and cite that eBay owns the company.
Hope that helps
