What is the explanation of the hadith "Five for which there is no expiation: associating partners with Allah, slandering a believer..." and what is the concept of expiation for each of the five categories, and what are examples of other major sins for which expiation is beneficial but were not mentioned in the hadith?

The Hadith (definition): "Five (sins) for which there is no expiation" is interpreted as negating the expiation of major sins by good deeds. Purification from these sins is only through repentance, or a prescribed punishment (hadd), or by God's forgiveness, based on the Prophet's (peace be upon him) saying: "The five daily prayers, Jumu'ah to Jumu'ah, and Ramadan (definition) to Ramadan, are expiations for what occurs between them, so long as major sins are avoided." As for expiation through repentance and hadd, it is established by other proofs, such as the Almighty's saying: "If they cease (disbelief), what has passed will be forgiven them," and His saying: "Except for those who repent, believe, and do righteous deeds; for them Allah will change their evil deeds into good ones." Whoever repents, and their repentance is sincere, Allah accepts it from them according to the majority (of scholars), but one should not feel secure from Allah's plan, as one does not know whether their repentance has been accepted or not. And whoever dies having committed a major sin without repenting from it, is under the Will of Allah. Some scholars have held the view that major sins are expiated by good deeds.