On computer
1.Login into your facebook account.
2.Go to the page whose link you’d like to copy
3.Select the URL above the page and right click on it
4.Now chose copy option,and your facebook page link will be copied, now you can share it wherever you want.
On mobile
1.Open the facebook app and login into your account
2.Go to the page whose link you’d like to copy
3.Click on the ‘More’ option with three dots you’ll see the following
4.Choose ‘copy link to profile’ from the above options and your facebook page link will be copied.