你可以试试这样的方法：

covid = pd.read_csv("https://covid.ourworldindata.org/data/owid-covid-data.csv")
covid.set_index("date", inplace=True)
covid.index = pd.to_datetime(covid.index)
df = covid.loc[covid.location=="Denmark", 'new_cases_smoothed_per_million']
g =  df.groupby(pd.Grouper(freq='M')).sum()
ax = g.plot.bar(figsize=(15,6), rot=0)
def line_format(label):
    """
    Convert time label to the format of pandas line plot
    """
    month = label.month_name()[:3]
    if month == 'Jan':
        month += f'\n{label.year}'
    return month

ax.set_xticklabels(map(line_format, g.index), fontsize=8);

输出量：