Think of a watershed as different areas of land facing down and connecting, which creates areas of drainage which drains to different trenches in the ground. This creates different bodies of water such as creeks, streams, or rivers which flow to larger bodies of water such as bays or a nearby ocean. This water is distributed along many areas of land.

 

If you still don’t understand, think of a watershed like a bowl or a funnel, in which all of the water drains to the bottom of the bowl/funnel and then channels into a body of water, in which it supplies many ecosystems and different organisms with the water needed to live.