What is meant by the phrase of al-Tirmidhi: "This is a good, sound hadith which we only know through this chain of transmission"?

Al-Tirmidhi’s saying, "Hasan Sahih" (good, authentic), indicates hesitation in describing the hadith as either authentic or good if it has a single chain of transmission. However, if it is narrated through multiple chains, it means that one of them is authentic while another is good.