I have got access to a pair of kettlebells (12 & 16 kg).
Can anyone please let me know what are the target muscles while swinging?
I hope they workout the gluteus and the hamstring.
Performing a proper two-hand kettlebell swing is a whole-body workout as opposed to isolating single muscles. However, the main muscles that go into swinging a bell are glutes, hamstrings, lower back + abs (core).
What you should aim for in a swing is to send your hips back (similar to deadlift form) with the bell, and then drive your hips forward to get the bell in motion. You do so by contracting the muscles described above.
The point is not to move the bell as high as you can by raising your arms, but to let the bell move naturally based on the amount of force you created through your hips driving forward.
There are many videos online describing this, but I would recommend ones that teach Russian style swings as opposed to American style swings, which overemphasize the height of the bell. Tim Ferris (4hr Body) has a really simple tutorial video here: https://www.youtube.com/watch?v=5zAkYWo_4ts.
Happy to help in any way.