cp
FilesPackage: coreutils
Copies files. Without -a the copy loses owner, timestamps and symbolic links; fine for a working file, wrong for a configuration or a backup.
What its options do in the lessons
From the same glossary the lessons render under their commands, so the two cannot disagree.
cp -r- Copies directories and their contents.
cp -a- Archive: a recursive copy preserving owner, group, permissions, timestamps and symbolic links. This is what you want when moving service files, which a plain copy would re-own to you.
cp -i- Asks before overwriting an existing file. Without it,
cpoverwrites silently. cp -n- Never overwrites: an existing file is left alone, with no question and no error.