Summarizing numeric columns

Here is a part of the famous Iris dataset loaded as iris_sample. The output of iris_sample.head() is:

+----+----------------+---------------+----------------+---------------+------------+
|    |   sepal_length |   sepal_width |   petal_length |   petal_width | species    |
|----+----------------+---------------+----------------+---------------+------------|
|  0 |            5.8 |           2.7 |            5.1 |           1.9 | virginica  |
|  1 |            5.2 |           2.7 |            3.9 |           1.4 | versicolor |
|  2 |            5.9 |           3   |            4.2 |           1.5 | versicolor |
|  3 |            4.8 |           3   |            1.4 |           0.1 | setosa     |
|  4 |            4.9 |           3   |            1.4 |           0.2 | setosa     |
+----+----------------+---------------+----------------+---------------+------------+

Insert one statement to generate descriptive statistics for numerical columns.