Adding information to a contact's profile allows you to specifically target or exclude them when receiving messages that do not fit their needs.
To do it :
Go to the Contacts tab
On mobile, click on More then on Contacts.
Find your contact by adding a filter to the list.
Once your contact is found, click on the contact's name.
Then click on Attributes to add information to the contact's name.
Click on Add Attributes at the bottom. In the fields that appear, enter a Name and a Value specifically representing the attribute you want to add to the profile.
Click on Save to complete the operation. The information will be added to the contact profile.
You can repeat the action for as many contacts as you want. You can then use this attribute to send targeted messages.