Teja loka uses radiance as a spiritual image: something understood inwardly becoming visible in how a person acts. On this board, the English label is Plane of radiation. The theme is symbolic rather than a claim about electromagnetic energy or a measurable aura.
You might think about the effect of a clear explanation, a dependable promise or someone's calm attention. An influence need not be dramatic to matter. Nor does it require displaying a special state to other people.
Square 58 is reached through ordinary movement. There is no requirement to visit 57 first and no devotion arrow to 58; the arrow from 54 leads to 68. For reflection, ask how an understanding you value could appear in a small, observable action.