You can use that table just don't display the fields in forms a user is allowed to edit and use the security component.
These values should be pretty self explaining:
- Position says it all: Its the position/order of the fields.
- Input, type of input, select, text, textarea...
- label, simply the label to be displayed
But it is up to you if you use the fields or not to generate the input fields based on these values.
The table is thought to store any kind of user information in a dynamic way, in fact it is like wp_postmeta.