add.cs

// Function that takes two integer (alredy declared as Intgers so as compiler can undertand) as input and
// Returns a output again of type integer 
int add(int a , int b){
  // Here also variable c is declared as Integer , any other type which compiler can not convert to like
  // will give error
  int c = a + b  
  return c 
}

add.py

# Python Program doesn't declares the type of variables and neither it provides the return type.
# The way the output of the function is handled defines the type it returns 
def add(a,b):
  # Here also if we see variable c is not assigned any type it assumes the type of a+b
  c = a+b 
  return c