What is the use of Import/Export in Outlook?

export/import functionality is used to backup and restore emails in the form of .pst extention.

backup email, contacts, and calendar

1. Select File > Open & Export > Import/Export.
2. Select Export to a file, and then select Next.
3. Select Outlook Data File (.pst), and select Next.
4. Select the mail folder you want to back up and select Next.
5. Choose a location and name for your backup file, and then select Finish.

Purpose is for backup restore the file

This Import/Export function in Microsoft outlook is mainly to take restoration and backups of mails. The form of file is .pst 

1. I have to select a file menu in outlook and have to go open and export and then select Import/Export

2. Later I have to select export to a file in computer directory and then select Next then have to select outlook date file which should be in .pst form and select next.

3. Select the mail folder you want to back up and select Next

4. Choose a location and name for your backup file, and then select Finish