Key Activities represent the "doing" of your business. They are the critical actions a company must take to operate successfully. If Key Resources are the fuel, Key Activities are the engine. Without them, the business cannot deliver its value proposition, reach its markets, or maintain its relationships.
For a company like eBay or Airbnb, the "key activity" is managing and continuously improving the online marketplace. Why Key Activities Matter key activities business model canvas
To see how Key Activities evolve, look at Netflix. Key Activities represent the "doing" of your business