EWS is a reservation introduced by the GOI. Now for EWS you will need to have a rank in CET which is said to the general rank and you will have a separate rank provided for category rank.

For example there are 5 students. And as per your score you have ranked 4. Now if among the 5 students there are 3 EWS students and you are one of those three. Now lets assume among you three 1 has scored higher than you and one has scored lower than you, then you will get your EWS rank 2. Thus when the admission will be provided you will be the second choice for the EWS seat.

I hope this answer helps.