Quick answer
It means the wire can safely carry significantly more current than an ordinary PVC wire of the same conductor size. The reason is the insulation: e-beam cross-linked insulation tolerates higher temperatures, and a higher temperature rating directly raises a cable's current-carrying capacity (ampacity).
In practice this gives you more headroom for heavy modern loads, cooler-running circuits and a longer life — or the option of a neater installation. APAR Anushakti HR-FR-LSH offers up to 50% more current-carrying capacity, and the e-beam Fire Protekt range up to 100% more.
Always still size to the load and have a licensed electrician confirm — see how to choose the right cable.