Dot is a multipurpose operator in Django templates. There are three different kinds of operations: attribute lookup, dictionary lookup, or list-index lookup (in that order).

In Python, first, let's define the context variables and classes:

>>> class DrOct:
        arms = 4
        def speak(self):
            return "You have a train to catch."
>>> mydict = {"key":"value"}
>>> mylist = [10, 20, 30]

Let's take a look at Python's syntax for the three kinds of lookups:

>>> "Dr. Oct has {0} arms and says: {1}".format(DrOct().arms, DrOct().speak())
'Dr. Oct has 4 arms and says: You have a train to catch.'
>>> mydict["key"]
'value'
>>> mylist[1]
20

In Django's template equivalent, it is as follows:

Dr. Oct has {{ s.arms }} arms and says: {{ s.speak }}
{{ mydict.key }}
{{ mylist.1 }}