The TSB is making a recommendation that IF you as a pilot decide to wear a parachute while flying a sailplane, you should know how to use it and in their recommendation that involves training and jumping at a skydive centre. It seems like common sense but most pilots quickly resolve thats not needed…what can go wrong?
Parachute training and jump conditioning will greatly increase your chances of a successful bale-out when below 3000 AGL ie close to the ground with little time to overcome the startle factor / brain freeze that jumping for the first time often results in. (Ive flown gliders and I’ve parachuted and I’ve been a jump pilot)
Although its standard practice for pilots of a single seat sailplane to wear a emergency chute, there is no regulatory requirement to wear a parachute and if you do, to show evidence of parachute training.