I think they mean that the callable/putable part is different from the convertible bond. So, it’s a convertible bond that is not callable or putable, not a convertible bond with no embedded option.
convertible bond is a straight bond that the you can convert into stock when ever you want ( you will do it if convert factor * stock price > straight bond value ).
callable and putable bond means you can have your Money back / or the issuer can pay you back.
so this means that a convertible bonds gives you a call option on stocks since you can CONVERT your bonds into stocks.
3 type of options :
callable : issuer can call back the bonds and give you your money
putable : you can pay back you bond
3 convertible : you can convert your bond into stock.