The line of fire is understood to mean the path of released energy, which we should keep clear of. For instance, falling objects, moving vehicles, slipping tools, etc. By keeping out of range, literally and figuratively, incidents and injuries are prevented. But this will not happen of its own accord. Identifying potential line of fire hazards before starting work, thinking about your own position during the work and the position of, for instance, your hands is very important. That is why we actively make our employees aware of safety hazards and show them how to deal with such hazards.
Some of the instruction videos used for this purpose: