I cannot grasp it because I am still too much of an infant. And so I lie there on my back, awkwardly and excitedly moving my arms and legs and making the noises a delighted baby makes because although I do not know and cannot say exactly what it is, I know it is mine. Its focus is on what we are rescued from. Well, this is part of what the New Testament word is trying to communicate. It is not merely rescue from something bad.
Salvation also has to do with being made whole, being made healthy, being healed.
Now, to be sure in the New Testament era, centuries before modern medicine, antibiotics and such, to be ill was to be in danger of dying. Even a scratch that became infected could lead to death. So, to be healed, to be made whole, was also a rescue from death. Thus when Paul wrote about salvation, he was not primarily focused on rescue from pain and punishment, here and hereafter. His focus was on the soul healing that makes it possible for us to be the persons God intends us to be.