Sorting allows you to rearrange your data by alphabetical order or by numeric value.
As an example in the below diagram I want to sort the names

I first highlight the area (I always do this if there is a lot of data with many columns and rows).
Note that in this example column B will also be sorted following column A.
I then go to Data / Sort


You will notice that there are several options. Play around with choosing different options. Or proceed with clicking on OK.

You can now see that the names are sorted by alphabetical order.