One can look at an comprehend 5 numbers. Nobody can comprehend 50 numbers, let alone 500 or 5000. Summary is needed. Summaries can be done in many ways.
Descriptive statistics is about data summaries.
Of course there are many ways to summarize, both many kinds of plots such as bar charts and scatter plots, and many kinds of numerical summary such as median and average. Different kinds of summary bring out different aspects of the data. A good plot may highlight some aspect not easily seen by looking at numbers.