Not quite correct. If you deal 5 damage to a 7 HP goblin, you have reduced the goblin below half its hit points, which according to the “describing the effects of damage” sidebar on PHB 197 means the goblin should be showing signs of wear such as cuts and bruises. If you had dealt 3 or fewer damage, the goblin would be showing no signs of injury. If you had done 7 or more damage, the goblin would be struck directly, leaving a bleeding injury or other trauma, or simply knock the goblin unconscious.