Make a beautiful binary string
Style


Read the PEP8 style guide!


Functions and variables should be snake_case
Conditions should be on the next line if a: ... is bad style
Conditions don't need parenthesis while (a) is the same as while a:
Avoid temp variables



Algorithm


Your first 2 guard clauses seem very unnecessary

When I remove them, the code still works.
Consider writing docstring/tests or both with the doctest module


Alternative Code

You could use re.findall(substring, string) for counting the occurrence, 

OR string.count(substring) making this practically a one-line

import doctest

def beautiful_binary_string(b):
    """
    Returns the steps to make a binary string beautiful

    &gt;&gt;&gt; beautiful_binary_string("0101010")
    2

    &gt;&gt;&gt; beautiful_binary_string("01100")
    0

    &gt;&gt;&gt; beautiful_binary_string("0100101010100010110100100110110100011100111110101001011001110111110000101011011111011001111100011101")
    10
    """
    return b.count("010")

if __name__ == '__main__':
    doctest.testmod()