Bergen is a rucksack basically. Your "home" when in the field.
Webbing is rig of belts and straps that you wear around your waist/over the shoulders to carry your immediate day to day equipment. Ammo, magazines, rations, water, respirator, first aid kit, etc. etc. Most units have a minimum amount of kit that has to be carried in it, most individuals have their own extras base don role/experience.
CFT = Combat fitness test:
In my day, the CFT was an 8 mile forced march to be completed within 2 hours with all of the above plus weapon, body armour, helmet and a minimum weight - usually 25 lb in the webbing and 40lb in the bergen. If you turned up light they added bricks to take you well over the minimum weight. Forward planning was essential. It all gets weighed at the end as well and if you're significantly under weight, you fail.
Followed by a 100m 'man carry' wearing everything above except the bergen but wearing your respirator to simulate a CASEVAC in and NBC environment. Considered at the time to be the most strenuous CASEVAC you might have to do. The carried man you had to carry his weapon and webbing as well and he had to simulate being unconscious and unable to help so he wouldn't carry his weapon. A proper bastard if he was the GPMG gunner!
Followed by a range shoot when you're well and truly chin-strapped and breathing through your arse. Fail any one of these and you fail the entire test.
Fuck me but they were good days. It probably explains why we could all drink 10 pints a night, eat about 8000 calories a day and still be whippet thin.