Objects are items that exist within the room. In your store, the most common objects you will see are the products you are selling. In this case, Cliff is standing in front of his bicycles. By turning on balloon help, we see that this actually represents 10 Racing Elite Racing Bikes.
Some objects have a special behavior. The radio will sometimes emit radio advertisements that a player has placed. If you click on your bike, you will bring up the Inventory window. You can tell when your mouse is over an object because the cursor changes from an arrow to a pointing finger.
Players are actually special objects. With balloon help on, we see that this picture of Cliff Chaput actually represents Cliff Chaput. Clicking on players lets you talk to them, or you can use the speech box on the main window. Players can be actual people, or they can be simulated, like the salesperson.
Placing the cursor over an exit turns it into the compass. With balloon help on, we can tell that Cliff is standing in front of a door leading to Tamara Avenue which will take us to the street outside.