Iterable can be anything for which items are received one by one, forward only. Built-in Python collections are iterable:
[1, 2, 3] # list, iterate over items
(1, 2, 3) # tuple
{1, 2, 3} # set
{1: 2, 3: 4} # dict, iterate over keys
Generators return iterables:
def foo(): # foo isn't iterable yet...
yield 1
res = foo() # ...but res already is