How do I counter the strategy, Giant (Level 6 or 7) ＋Healer combo?

To counter the giant and healer combo, you need to place your defensive buildings evenly in your village and maximize the use of traps and bombs.
It is most advisable to have a layout that has many sections divided by walls.
Giants need to destroy walls first to get into destroying your defensive buildings, so strong walls are necessary to slow down the giants.
Place your spring traps into areas that giants will most likely to pass.
Giants targets the defensive buildings first so put the spring traps near your defensive building as well as your bombs.
Place your clan castle in the middle of your village.
Once inside, the giants cannot fight back to the reinforcement troops inside your clan castle.
Your reinforcement troops will be a great help in taking them one by one without them fighting back.
Also put your barbarian king and your queen archer in the middle so that they can help in killing these giants.
The healer however will help keep the giants health from dropping, so killing the healer the earliest is a crucial part of this strategy.
Place your air defenses evenly on your base.
This is the best way to kill the healers fast.
This way, they can attack the healer from whichever side the enemy will attack.