Update to macOS 26.1.
In general, either Homebrew is not installed, or the Homebrew installation has not been completed and the necessary Homebrew directories have not been added into your path. Probably something related to the latter.
The contents of the environment variable PATH is an ordered list of places to look for commands you enter, with zsh and most other shells separating each of those places with colons.
zsh can read from various scripts at login. Those scripts are ~/.zprofile , ~/.zshenv, ~/.zshr, and ~/.zlogin, and ~/.zlogout.
You can cat each of those script files, if present. You can edit with nano, if you want to alter the file.
And to add your own stuff to the path in zsh, use (lowercase) path as follows to prepend or append the directory:
path+=('/path/to/wherever')
path=('/path/to/wherever' $path )
This same sort of path change is what Homebrew is doing during their installation and setup, though I don’t know which script the Homebrew folks use for the path.
Looking at the Homebrew docs, this is probably the step that was missed:

Details: https://docs.brew.sh/Installation