It's a way to identify them without errors.
Sometimes seen in schematic diagrams and my preferred way of displaying the value.
In this instance 6K8 means 6,800 ohm.
Also along the same lines, say 68 ohm(68R) 4.7ohm (4R7) and say a 0.1 ohm (0R1)
for the suffix letters , check out wiki (K,M etc.) and the differences between say M and m.....consider it homework