Функция:
def number_tracks(df,day,city):
    track_list = df[(df['weekday']==day)&(df['city'] == city)]
    track_list_count = track_list['genre_name'].count()
    return track_list_count

Вызовы функции:
number_tracks(df,'Monday','Moscow’)

number_tracks(df,'Monday','Saint-Petersburg’)

number_tracks(df,'Wednesday','Moscow’)

number_tracks(df,'Wednesday','Saint-Petersburg’)

number_tracks(df,'Friday','Moscow’)

number_tracks(df,'Friday','Saint-Petersburg’)

Сведение данных в одну таблицу:
data = [['Moscow', 15347, 10865, 15680],
       ['Saint-Petersburg', 5519, 6913, 5802]]
columns = ['city','monday','wednesday','friday']
table = pd.DataFrame (data=data, columns=columns)
table