check the steps below in explanation.
Explanation:
To split the Customer Name field into two fields named First Name and Last Name, you need to do the following steps:
Open the link to Book1 found on the desktop. This will open the Tableau workbook that uses the Superstore data source.
Go to the Data Source tab at the bottom of the workbook to see the data source page. You will see a table that shows the fields and values from the Superstore data source.
Right-click on Customer Name in the table and select Split from the menu. This will split the field into two fields based on a separator, which is a space by default. You will see two new fields named Customer Name - Split 1 and Customer Name - Split 2 in the table.
Right-click on Customer Name - Split 1 and select Rename from the menu. Type First Name as the new name and press Enter. This will rename the field as First Name.
Right-click on Customer Name - Split 2 and select Rename from the menu. Type Last Name as the new name and press Enter. This will rename the field as Last Name.
References: https://help.tableau.com/current/pro/desktop/en-us/datasource_prepare.htm
https://help.tableau.com/current/pro/desktop/en-us/split.htm
https://help.tableau.com/current/pro/desktop/en-us/renamefield.htm