This configuration section is very simple.
enabled:
Should barbed wire (cobwebs) hurt players when they walk into the wire?
true|false
This is true by default.
damage:
This option can be set between 0 - 40, and this represents the number of hearts that a player has.
20 is full health, and 1 is half a heart. You can set this value up to 40 so that you can also damage armour.
damage is set to 2 (one heart) by default.