Letters hold no meaning. The ls, mv, cp, rm commands are self-explanatory with only one extra letter.
The issue there is that's dangerously close to 'rm'! I'll stick to 'mv' thanks.
They really aren't :)
If you came across them outside of the context in which you learned them, they mean nothing.
Once you've learned them, only then do you know that they are contractions/abbreviations: ls is list, mv is move, cp is copy etc.
Now I have them internalised, so it's fine.