Macos – Mac OS: Unable to expand zip file

Mac OS. I am unable to expand zip file. I have tried this:
Unzip in Terminal:

1. Open Terminal.
2. Type unzip and a space, then drag/drop the zip file into the Terminal window.
3. Press Enter and the zip file will be unzipped, storing all files on your computer.

When I try to open the zip file, it reads:

unable to expand (error 1- operation not permitted).

Online, p7zip seems to be recommended. Here are instructions:

You can install it via MacPorts or Homebrew with these commands, respectively:

sudo port install p7zip
brew install p7zip

Then, to unzip it, use:

7za x file.zip

Please explain the steps to enter this code, I don’t know what it means. But I am glad to learn a new thing!