The calculated distance (air line) between Kastsyukowka and Svyetlahorsk is approximately 50 miles respectively 80 kilometers.
By car or train, the actual journey to Svyetlahorsk is certainly longer, as only the direct route (as the crow flies) between Kastsyukowka and Svyetlahorsk has been calculated here.
Air line (approximately)
80 kilometers
43 nautical miles