Text file to spreadsheet
There are a few things we could improve:


you could use the "lazy" glob.iglob() to filter out *.txt files instead of doing the os.listdir(), keeping the whole list if memory and having an extra check inside the loop:

for filename in glob.iglob("*.txt"):

instead of using textfile.readlines() and read all the lines in a file into memory, iterate over the file object directly in a "lazy" manner:

for line in textfile:

instead of manually keeping track of column value, you could use enumerate():

for column, filename in enumerate(glob.iglob("*.txt"), start=1):


Same idea could be applied for rows.
I think you don't have to use get_column_letter() and instead operate the numbers which you have:

sheet.cell(row=row, column=column).value = line

not to say anything against openpyxl, but I personally find xlsxwriter module's API more enjoyable and more feature rich




Complete improved version:

import glob

import openpyxl


def text_into_spreadsheet():
    """main logic for read .txt into spreadsheet"""
    workbook = openpyxl.Workbook()
    sheet = workbook.active

    for column, filename in enumerate(glob.iglob("*.txt"), start=1):
        with open(filename) as textfile:
            sheet.cell(row=1, column=column).value = filename

            for row, line in enumerate(textfile, start=2):
                sheet.cell(row=row, column=column).value = line

    workbook.save('result.xlsx')


if __name__ == "__main__":
    text_into_spreadsheet()