What does it mean to replace the second-class seat with a soft sleeper?

Soft sleeper instead of second-class seat means soft sleeper instead of second-class seat. Sleeper cars are private rooms, with 4 beds, 2 upper bunks and 2 lower bunks in a private room. People are not allowed to lie on the upper bunk. There are 2 beds in the lower berth, each bed seats 3 people. So in fact, it is just to change the second-class seat into a sleeper.

Extended data:

The second-class seat of EMU is a type of passenger train seats in China's national railway, all of which are located in the carriages of EMU running on the national railway line, so it is also called the second-class seat of EMU (group).

At present, second-class seats are only available in national railway EMUs, including high-speed EMUs (G trains), ordinary EMUs (D trains), intercity EMUs (C trains) and regional EMUs (S trains). The second-class seats in most EMU models meet the standards of soft seats in terms of material requirements, but there are also a few models (such as CRH6 EMU), and the comfort of second-class seats is only equivalent to the hard seats in traditional trains.

In the case of no discount, the second-class ticket price is equal to the no-seat ticket price of EMU, which is lower than the first-class ticket price and higher than the hard sleeper and soft sleeper ticket price. All national railway EMUs are equipped with second-class seats, which are also the lowest-level seats of national railway EMUs.

References:

Train second class _ Baidu Encyclopedia