How to move array list of values into different columns in Pandas DataFrame?

Use df.join:

import itertools
import string

names = list(
    itertools.chain(
        string.ascii_uppercase, 
        (''.join(pair) for pair in itertools.product(string.ascii_uppercase, repeat=3))
))


df = pd.DataFrame([[range(1,1000)]],columns=['A'])
df = df.join(pd.DataFrame(df["A"].apply(pd.Series))).drop('A',axis=1)
df.columns=names[:999]

Assuming your df to be this:

In [924]: df = pd.DataFrame({'A': [{1,2,3}]})

In [925]: df
Out[925]: 
           A
0  {1, 2, 3}

You can do this:

In [935]: result = pd.DataFrame(df.A.tolist())

In [936]: result
Out[936]: 
   0  1  2
0  1  2  3