The sort options helps you to arrange the rows in an ascending or descending order with respect to the values on one or more columns.
For example you can sort the sheet to show the employees details in an descending order in terms of the number of hours they worked.
To sort the sheet, click on the sort option in the top bar. A drop down will appear in which you can select the column(s) you want to sort by and whether to sort first to last or last to first for single select and multi select columns,0-9 or 9-0 for numeric values and A-Z or Z-A for text based inputs.
To delete a sorting constraint that you have in you have in your sheet you can click on the cross at the end of the constraint.
You can read about the operators that can be used for each column type here.