qry=Contacts.select().where (Contacts.City=='Nasik').count()
print (qry)

from peewee import *

db = SqliteDatabase('mydatabase.db')
class Contacts(BaseModel):
   RollNo = IntegerField()
   Name = TextField()
   City = TextField()
   class Meta:
      database = db

db.create_tables([Contacts])

qry=Contacts.select(Contacts.City, fn.Count(Contacts.City).alias('count')).group_by(Contacts.City)
print (qry.sql())
for q in qry:
   print (q.City, q.count)

('SELECT "t1"."City", Count("t1"."City") AS "count" FROM "contacts" AS "t1" GROUP BY "t1"."City"', [])

Chennai 1
Delhi   2
Indore  1
Mumbai  1
Nagpur  1
Nasik   3
Pune    1