These show the distance you are from Moscow and every tenth of a kilometre there are smaller markers. Each carriage is supervised by two stewards, each working twelve hours on and twelve hours off and thus giving you a twenty four hour service throughout the journey. Each cabin on the train is individually air conditioned and temperature controlled. The stewards can adjust the climate of each cabin independently from a control panel in their cabin. As a result, certainly in first class, the journey on board can be quite pleasant whatever the weather outside.
Most people seem to travel in light clothing, track suits or even pyjamas when on board.
Of course outside is another matter. Each power socket in the carriage is also individually controlled by the stewards. I met someone with a video camera who used the to charge the battery, but they had to ask the steward to switch on the power to the socket every time they needed to use it. The sockets deliver 240 volts. Another useful service provided by the stewards is the ever boiling samavar just outside their cabin.