hey,
EWS is the Economically Weaker Section of the society and GGSIPU has seats reserved for EWS quota students.
You can avail the EWS quota if your family's income from all sources is less than as defined in the criteria.So an income certificate will be required.
EWS seats have been taken from the general category seats and so no, you do not necessarily need to be from Delhi to avail this quota, however preference will be given to students of Delhi as it is a government college in Delhi so there are seats reserved for them even in the general category.
Once it is approved and you get admission then you will be granted financial assistance for your education in the college.