KN is the unit of force, and tons and kilograms are the units of mass. They are different physical quantities with different physical dimensions, so the units of force and mass cannot be directly converted.
If there is a gravitational acceleration g≈ 10 Newton/kg, it can be transformed.
49KN = 49000N = 4900N ÷10N/kg = 4900kg = 4.9 tons.
Others:
Ton is often used as a mathematical unit of mass, and it is often used to measure the weight of larger items in life.
Mass unit, metric ton is equal to 1000 kg: ~ digits. ~ kilometers (one kilometer per ton of goods).
American unit of mass or weight. Britain is British tons, and America is American tons.
Some industries use tons to mark the volume of tanks: in fact, the water quality of 1 m3 is about 1 ton.
For example, 1t compressed air storage tank: 1m3 or 1000L storage tank volume, 10t reactor: 10m3 or 10000L reactor capacity.