Restricting access to a column

1. Go to the options of the concerned column.
2. Select Restrict Access.

Settings: 

Default:

The members have Read/Write access.

It is possible to restrict or modify new members' access though the first option:

Restriction options:

• Read/Write: The member can see and modify the column.
• Read only: The member can only see the column but not modify.
• Hidden: The member can neither see nor modify the column.