Select File, then navigate to Open & Export > Import/Export.
The next step is to select Export to a file, then go to Next.
Choose Comma Separated Values, then Next.
Now, under the email account you wish to export contact from, click on Contacts.
Select the Browse option, then navigate to the area you want to save your contacts.
Type the file name, then hit the OK button > Finish, and that's it.