Question about message at the end of python installation

[quazi-irfan]

I am under the impression that if I do brew install x then homebrew installs the package at /opt/homebrew/Celler/x, and the binary is symlinked to /opt/homebrew/bin. I have installed python3.9 and now have python3.9 symlink available at /opt/homebrew/bin, which is pointing to /opt/homebrew/Celler/python@3.9/3.9.16/bin/python3.9. So far so good.

But at the end of python3.9 installation, I saw this message that I didn't understand,

Unversioned and major-versioned symlinks `python`, `python3`, `python-config`, `python3-config`, `pip`, `pip3`, etc. pointing to `python3.9`, `python3.9-config`, `pip3.9` etc., respectively, have been installed into 
  /opt/homebrew/opt/python@3.9/libexec/bin 

I have the following questions about this message,

1. Why is homebrew installing package content outside of /opt/homebrew/Celler?
2. What are these inversion and major-versioned symlinks being referred to?
3. How does homebrew prevent collision with the default system python installation?

[SMillerDev]

Why is homebrew installing package content outside of /opt/homebrew/Cellar

/opt/homebrew/opt/python@3.9 is symlinked to /opt/homebrew/Cellar/python@3.9/<latest_version_here> so that you don't need to update any usage when software updates a version.

What are these inversion and major-versioned symlinks being referred to?

Exactly what is in the list there. Symlinks for python that only indicate a major version or no version at all.

How does homebrew prevent collision with the default system python installation?

By installing somewhere else.