When multiple values are stored in a single column of data, you may want split the values into separate columns. This would allow you to better interact with each component. For example, it is not uncommon to get a "Full Name" column that contains both the last name and first name in it, or sometimes you want to use just the domain of an email address.
Before starting, determine if you want to overwrite the original column. This is the default in Excel. You should also figure out where you want the results to go because it is much easier to create the destination for the data first before you start the split exercise. In Excel, I have found the easiest way to split data that is simply organized is to use the "Text to Columns" features.
Select the column that you want to split
Click "Text to Columns" on the data ribbon
In this example, the data is separated by a comma, so select "Delimited", then click Next.
Un-check Tab, check Comma, click Next.
Change the Destination so you don't overwrite the original data, click Finish
Rename the columns
Bring up the column menu on the "Full Name" column, then select Split
Remove "Full Name (3)" by clicking on the minus button next to it.