Update stdtypes.rst

Doc/library/stdtypes.rst

@@ -4509,7 +4509,7 @@ can be used interchangeably to index the same dictionary entry.
  dictionary is created by calling :meth:`~object.__getitem__` on the argument with
  each returned key from the method. Otherwise, the positional argument must be an
  :term:`iterable` object. Each item in the iterable must itself be an iterable
- with exactly two objects. The first element of each item becomes a key in the
+ with exactly two elements. The first element of each item becomes a key in the
  new dictionary, and the second element the corresponding value. If a key occurs
  more than once, the last value for that key becomes the corresponding value in
  the new dictionary.