Split data from single CSV file into several CSV files by column value
Don't use string literals as comments. PEP 8 explains how to use comments.
Docstrings should use """ rather than ''', as described in PEP 257. Also your docstring doesn't need the "-", and should probably be rephrased slightly to fit on one line.
Close files, #fb.close() shows you went out of your way to make bad code. Without fb.close or wrapping open in a with, the file is not guaranteed to be closed. I personally prefer with to fb.close, as described here.
Personally, rather than over-riding your files \$n\$ times, I'd use collections.defaultdict, to group all your files into their rows.
You may want to change get_file_path, to be based of __file__. Or leave your path to be relative, as it'll default to that behavior.




import os
import csv
from collections import defaultdict

FILE_DIR = os.path.dirname(os.path.abspath(__file__))


def get_file_path(filename):
    return os.path.join(FILE_DIR, filename)


file_path = get_file_path('argos.csv')
with open(file_path, 'rU') as csvfile:
    reader = csv.reader(csvfile)
    header = next(reader)
    data = defaultdict(lambda:[header])
    _ = data[header[5][:5]]
    for row in reader: 
        data[row[5][:5]].append(row)
    for file_name, rows in data.items():
        with open(file_name, 'w+') as f:
            for row in rows:
                f.write(str(row) + '\n')