These lines indicate a certain effect inherent to the gun. The text itself often gives a hint of what that special ability does. Sometimes the description relates to the boss or enemy who dropped the weapon.

If you're having a problem finding out what special ability your red-text weapon has, try searching on the internet. Maybe someone has found out it's effect and posted about it.

Sources:[Borderlands Wiki][1],[Gearbox Forum][2]


  [1]: http://borderlands.wikia.com/wiki/Special_Weapon_Effects
  [2]: http://forums.gearboxsoftware.com/showthread.php?t=150835