What do you mean by SL,1A,2A,3A,2S,CC in train?

Different Classes of Travel :
SL : Sleeper Class
1A : First AC
2A : Second AC (Sleeper)
3A : Three Tier AC (Sleeper)
2S : Second Sitting
CC : AC Chair Car

1A-
First Class AC:
This is the most expensive class, with fares which can be on par with airlines. Bedding is included with the fare in IR. This air conditioned coach is present only on popular routes between metropolitan cities and can carry 18 passengers. The coaches are carpeted, have sleeping accommodation and have privacy features like personal coupes.Can carry 18 passengers.

2A-
AC-Two Tier:
Air conditioned coaches with sleeping berths, ample leg room, curtains and individual reading lamps. Berths are usually arranged in two tiers in bays of six, four across the width of the coach then the gangway then two berths longways, with curtains provided to give some privicy from those walking up and down. Bedding is included with the fare.Can carry 48 passengers.

3A-
AC-Three Tier:
Air conditioned coaches with sleeping berths. Berths are usually arranged as in 2AC but with three tiers across the width and two longways as before giving eight bays of eight. They are slightly less well appointed, usually no reading lights or curtained off gangways. Bedding is included with fare.Can carry 64 passengers.

FC-
First Class:
Same as 1AC, without the air conditioning.Such coaches are not very common.

CC-
AC Chair Car:
An air-conditioned seater coach with a total of five seats in a row used for day travel between cities.

EC-
Executive Class Chair Car:
An air-conditioned seater coach with a total of four seats in a row used for day travel between cities.

SL-
Sleeper Class:
The sleeper class is the most common coach, and usually up to ten coaches could be attached. These are regular sleeping coaches with three berths vertically stacked. In broad gauge.Can carry 72 passengers.

2S-
Seater class:
Same as AC Chair car, but without the air-conditioning.

G-
General:
The cheapest accommodation, with seats made of pressed wood. A seat may not be guaranteed and tickets are issued usually two hours before the scheduled departure of the train. These coaches are usually heavily crowded...