Larger data sets tend to have duplicate content. You may have a list of multiple contacts in a organization and only want to see the number of organization you have or you have multiple rows of same type of data . In situations like this, removing the duplicates comes in quite handy.
To remove your duplicates, highlight the row or column that you want to remove duplicates of. Then, go to the Data tab, and select "Remove Duplicates" (under Tools). A pop-up will appear to confirm which data you want to work with. Select "Remove Duplicates," and you're good to go.