希望下面的片段是你正在寻找的：

import seaborn as sns
import pandas as pd

df = pd.read_csv("student_data.csv") #assuming the data is in the csv file

# get only month and year from datetime column (date of exam)
df['date_col'] = df['Date_of_exam(d/m/y)'].dt.to_period('M') 

# group by based on month and year after filtering poor graded students
data = df[df['Student_Performance']=='Poor'].groupby(['date_col']).size().reset_index(name
    = 'count')  

ax = sns.barplot(x="date_col", y="count", data=data) #plot using seaborn

输出：