meteor npm install --production - meteor

Question

What does these lines mean
meteor npm install --production
meteor npm install --save
?
The Docs explains the command meteor npm <pacakge name> So the npm package is install, but what does the flag --production and --save do?

Answer 1

The meteor npm command simply forwards the arguments that follow it to Meteor's bundled npm version, so it behaves as the npm command-line tool.
The basic command is meteor npm <command and arguments.
This basic install command is meteor npm install <package name> rather than meteor npm <package name>.
Its relevant documentation is therefore not the one you referenced in your question, but the npm's CLI tool's (you referenced npm's install package, note the npm install install there).
NPM creates a package.json file and lists the project's dependencies there. You use the --save flag to instruct npm to add the packages installed to the dependencies file and the --production flag to instruct npm to not install its dev-dependencies, which are dependencies that were used for developing and debugging this package, but are not strictly required for its operation in production.
Take the time to familiarize yourself with the tool.
From the CLI docs:
npm install (with no args, in package dir)
npm install [<#scope>/]<name>
npm install [<#scope>/]<name>#<tag>
npm install [<#scope>/]<name>#<version>
npm install [<#scope>/]<name>#<version range>
npm install <tarball file>
npm install <tarball url>
npm install <folder>
alias: npm i
common options: [-S|--save|-D|--save-dev|-O|--save-optional] [-E|--save-exact] [--dry-run]
-S, --save: Package will appear in your dependencies.
With the --production flag (or when the NODE_ENV environment variable is set to production), npm will not install modules listed in devDependencies.