To select multiple columns in a Pandas dataframe, you can pass a list of column names to the dataframe indexing operator []. Here are a few examples:

1. Selecting two columns 'col1' and 'col2':

df[['col1', 'col2']]

2. Selecting three columns 'col1', 'col2', and 'col3':
df[['col1', 'col2', 'col3']]

3. Selecting a range of columns, from 'col1' to 'col3':
df.loc[:, 'col1':'col3']

4. Selecting columns using a boolean mask:
df.loc[:, [True, False, True]]

Note that in all of these examples, the resulting object will be a new dataframe that includes only the selected columns. If you want to modify the original dataframe, you can assign the result back to the original dataframe:
df = df[['col1', 'col2']]