It looks like a cannonball with a handle, but don't be fooled - Russian kettlebell is the ultimate muscle tool used in Russian special force unit and now becoming popular in UK and US.
Kettlebell training is suppose to bring 10 times the effects of weight lifting. Kettlebells come in 'poods'. A pood is an old Russian measure of weight, which equals 16kg, or roughly 35 lbs. An average man should start with a 35-pounder. It does not sound like a lot for a weight lifter but believe it; it feels a lot heavier than it should! Most men will eventually progress to a 53-pounder, the standard issue size in the Russian military. Although available in most units, 70-pounders are used only by a few advanced guys and in elite competitions. 88-pounders are for circus freaks.
An average woman should start with an 18-pounder. A strong woman can go for a 26-pounder. Some women will advance to a 35-pounder. A few hard women will go beyond.

The track with kettlebell should usually look something like that:

1. 5-10 sets of 1 arm swings. Rest a full minute between each set. Keep the form super tight; don't worry about swinging the bell above the
waist.

2. 2-3 sets of box squats - hold the bell by the horns in front of you, same feeling as 'reaching back with your butt to sit on a bench'. The bench should be at a comfortable height, lower it over the weeks as you get more flexible and balanced until you are practically sitting on the floor.

3. Overhead (Military) press - 2-3 sets of 3-4 on each side.
4. Windmills 2-3 sets of 3 on each side.
5. Power crunches or 'rollback' sit-ups to taste.

Start out learning the first 2 exercises and introduce a new exercise every week or so (unless you are impatient to proceed). Alternate hard and easy days, try to lift 4-6 times a week for 10-30 minutes to keep your muscles and nervous system in 'grease the groove' mode.