I would like to briefly elaborate.
The two definitions of terrorist group are “a listed entity” or “an entity that has as one of its purposes or activities facilitating or carrying out any terrorist activity”. For example, if there were a hateful group, a white power group, that does a terrorist act but is fundraising for various purposes, including perhaps its publications, the day after the terrorist act, it would probably not have been listed yet, because there would not have been time to do so.
Right now, as the law stands, it would be against the Criminal Code, potentially, to give money to that organization because it is a terrorist group, albeit unlisted. The effect of this amendment would be to remove that potential liability.