Have you ever searched for sound effects or photos online? Without proper searchable terms (ie keywords) can make it an impossible task to find your desired media!
For example you need a relaxing sound at beach when the sun is setting. The keywords or tags could look like calm, ocean, waves, beach, sunset.
You might think why would I use sunset as a keyword in a sound effect, that doesn’t create a sound? It is an important keyword to describe a moment, time, and emotions. Ocean sounds are different in the evening than in the morning.