what is value of '2' and value of '1' means in this code ?

[vishnuvardhan58]

if (box[4] == 'crop'):
masks[row_s:row_e, col_s:col_e, i] = 2
class_ids.append(self.class_names.index('crop'))
else:
masks[row_s:row_e, col_s:col_e, i] = 1
class_ids.append(self.class_names.index('weed'))

what does 2 mean in masks[row_s:row_e, col_s:col_e, i] = 2 ?
what does 1 mean in masks[row_s:row_e, col_s:col_e, i] = 1 ?

How do I make changes in this part if I have 5 classes in my dataset ?