As a disclaimer, while I do help work on these issues for open source projects and am a co-author of PEP 639, I am not a lawyer, and this is not legal advice.
With that out of the way, you can see at the bottom of every page of the docs,
© Copyright 2001-2021, Python Software Foundation.
This page is licensed under the Python Software Foundation License Version 2.
Examples, recipes, and other code in the documentation are additionally licensed under the Zero Clause BSD License.
See History and License for more information.
In particular, per the PSF license,
Subject to the terms and conditions of this License Agreement, PSF hereby
grants Licensee a nonexclusive, royalty-free, world-wide license to reproduce,
analyze, test, perform and/or display publicly, prepare derivative works,
distribute, and otherwise use Python 3.10.1 alone or in any derivative
version, provided, however, that PSF’s License Agreement and PSF’s notice of
copyright, i.e., “Copyright © 2001-2021 Python Software Foundation; All Rights
Reserved” are retained in Python 3.10.1 alone or in any derivative version
prepared by Licensee.
So long as the book meets the relatively minimal conditions of the license, namely including the full text of the license agreement and the PSF’s copyright notice, summarizing any changes therein (simply stating it is a translation and mentioning any added content would probably suffice), and not using the PSF tracemarks in a way that would imply endorsement or a relationship between the book and Python/PSF, it is perfectly legal. Similarly, they could sell CDs with Python (and or/other software) on them, or a commercial software package that included Python (as is routinely done), so long as they follow the minimal conditions of the license. In fact, it is even possible to resell GPL, GFDL and CC-BY-SA-licensed works (e.g. many books just reprint Wikipedia), so long as the (somewhat more involved) conditions of the license are followed.