Those are a very specific subsection of lies, where you say somebody did something they didn’t do or besmirch their character in a way they can prove what you said was detrimental. It’s perfectly okay to say things like ‘let’s build a wall and make Mexico pay for it’ or ‘those shoes really suit you’ because there’s no libel there.

Also, you’re free to libel/slander someone (most of the time) because the burden of proof for libel is quite high. It’s a difficult thing to prosecute - as Johnny Depp found out over here a few months back.