Adding a user to a Google Analytics profile allows that user to view reports for the website/profile by logging into their analytics account. Adding an admin means that they can add new users, create new reports etc.
Here is how to add a user/admin
- Go to google.com/analytics and log in
- Once logged in, select the profile which you want to share with the user
- When you are in the profile, click under admin on the nav bar on the top right
- Select the profile again
- Click on Users and on + New User
- Provide the email address for user, pick if you want them to be admin and if you want to notify them via email and click on Add User
This will allow the user with the email address to access reports for this profile under their Google Analytics account.