Men who are new to kettlebell training and lifting in general should start with a 12 KG or 26 LB kettlebell. This is the ideal weight for the average man, new to weights or with a bench press strength of under 200 pounds. A 12 kg or 26 Lb kettlebell is ideal for this same man to perform isolation movments like presses and get ups.
Men who are new to kettlebells, but not weight training or who have a higher bench press should start with a 44 pound or 20 kilogram kettlebell for explosive movements. It is hard to make recommendations without knowing you specifically, but this is where most would start.