What do the files in bin folder actually used for?

Question

I am currently working on a node project that requires eslint as a dependency. Hence, a file named eslint and eslint.cmd was created automatically in the root_directory/node_modules/.bin folder.

The content of the eslint file is -

basedir=$(dirname "$(echo "$0" | sed -e 's,\\,/,g')")

case `uname` in
    *CYGWIN*) basedir=`cygpath -w "$basedir"`;;
esac

if [ -x "$basedir/node" ]; then
  "$basedir/node"  "$basedir/../eslint/bin/eslint.js" "$@"
  ret=$?
else 
  node  "$basedir/../eslint/bin/eslint.js" "$@"
  ret=$?
fi
exit $ret

Can someone give a line-to-line explaination to what exactly this code is doing?

I read the answer on What is the purpose of .bin folder in node_modules?
Still couldn't figure out how this code does all that is stated in the answers.

node version - 12.10.0
npm version - 6.10.3