Hi. Radially in this context comes from the construction of cylindrical electrolytic capacitors which can have leads oriented radially (not in axis but offset, both on same side) or axially (in axis, one per side).
Other components can also have same/similar construction. Most popular fuse designs with leads are actually axial, usually 5x20 with leads. The advantage of radial design is that you do not have to shape the leads to populate the board. You just cut the leads and put into THT holes. With radial design you need lead shaping (which comes at a cost and creates problems of its own).