How to select specific Dataframe columns for transformation with ColumnTransformer in Python?

I was going through a code that I found on the web which uses the indexing technique to select columns when applying transformations to columns using the ColumnTransformer available in sklearn. However, I was wondering if there are different alternative ways of doing this selection, if there are please let me know because remembering indexes for columns can be a hard task. I am attaching a sample dataframe code that you can use and I am also attaching the code I found.

Sample Dataframe:

Indexing code I found: