Convert month abbreviation to full name

I have this function which converts an English month to a French month:

def changeMonth(month):
    global CurrentMonth
    match month:
        case "Jan":
            return "Janvier"
        case "Feb":
            return "Février"
        case "Mar":
            return "Mars"
        case "Apr":
            return "Avril"
        case "May":
            return "Mai"
        case "Jun":
            return "Juin"
        case "Jul":
            return "Juillet"
        case "Aug":
            return "Août"
        case "Sep":
            return "Septembre"
        case "Oct":
            return "Octobre"
        case "Nov":
            return "Novembre"
        case "Dec":
            return "Décembre"

        # If an exact match is not confirmed, this last case will be used if provided
        case _:
            return ""

and I have a pandas col df["month"]= df['ic_graph']['month'].tolist():

now what I'm looking for is to pass the df["month"] col through the changeMonth function to display the df["month"] in frensh months

By the way, I do not want to use the

>>> import locale
>>> locale.setlocale(locale.LC_ALL, 'fr_FR')

Question seems a bit unclear to me,
Do you want to replace the month column in dataframe itself?
If yes something like this can work:

def changeMonth(month):
    if month=="Jan":
            return "Janvier"
    elif month=="Feb":
            return "Février"
    elif month=="Mar":
        return "Mars"
    elif month=="Apr":
        return "Avril"
    elif month=="May":
        return "Mai"
    elif month=="Jun":
        return "Juin"
    elif month=="Jul":
        return "Juillet"
    elif month=="Aug":
        return "Août"
    elif month=="Sep":
        return "Septembre"
    elif month=="Oct":
        return "Octobre"
    elif month=="Nov":
        return "Novembre"
    elif "Dec":
            return "Décembre"

    # If an exact match is not confirmed, this last case will be used if provided
    else:
        return ""

df['month']=df['month'].apply(changeMonth)

But if you want to change the month while just printing the list out, you can use list comprehension,

french_month_list = [changeMonth(i) for i in df['ic_graph']['month'].tolist()]