Python Primes iterator using count()

I am trying to understand how the primes iterator works, the code was taken from a lecture. I searched for count() but found only methods for lists, objects, I just do not understand how the line self._candidates = count(1) works and what it means. where is the object we are trying to count 1 in? and the further use of it self._candidates.next() is also very confusing. I mainly code in java albeit know basic python. here is the code:

class Primes(object):
    def __init__(self):
        self._candidates = count(1)
    def __iter__(self): return self
    def next(self):
        item = self._candidates.next()
        if item > 1:
            self._candidates = FilterMultiplies(self._candidates, item)
        return item

class FilterMultiplies(object):def __init__(self, seq, n):
    self._seq = iter(seq)
        self._n = n
    def __iter__(self): return self
    def next(self):
        item = self._seq.next()
        while item % self._n == 0:
            item = self._seq.next()
        return item