As ‘thistle’ directed above, the Catechism really is your best starting point with this question (and so many others).
Many people ask about this line in the Creed. The general POV of the questioning I encounter is, “how could ‘God’ go to hell?”
But ‘God going to Hell’ is not what is being put forward in the phrase.
I have pulled a couple of lines out of the CCC and added the emphasis to help my discussion.
CCC 636-637: By the expression “He descended into hell”, the Apostles’ Creed confesses that Jesus did really die and through his death for us conquered death and the devil “who has the power of death” (Heb 2:14). In his human soul united to his divine person, the dead Christ went down to the realm of the dead.
A very important Christological situation comes to the surface in this line of the creed, the human Jesus and the divine Jesus, the two, ever-present, ever-united natures of Jesus.
So, it’s a very important item to profess, because it declares Jesus was truly human - his truly human soul ran the course of all truly human souls at and after death. That’s how truly human he was and that’s how truly dead he was. Jesus redeemed us as man and by dying. He became man and obeyed the Father as no man had, even to the point of death - real death. Questioning his humanity and/or the thoroughness of his dead-ness immediately calls into question **our **redemption. Also, to question the absolute-ness of his death necessarily questions the nature/complete-ness of his resurrection from the dead. (For example, you have probably heard secularists explaining away the miracle of the resurrection with “not really dead/comatose” theories)
Historically, in the development of the Creed in the early church, it may have become necessary to stress this point of ‘descent into hell’ to combat the rising tide of Arian heresy which generally held Jesus was not truly human, but a divine spirit with ‘a human appearance.’
However, Jesus was as human as you or I, and when he died his human soul experienced what your and my human souls will experience - in as much as departing the body and going* ‘somewhere’.* That’s how truly human and dead he was.
Now I am going to enter the waters of speculation. One might be correct in saying that the human soul of Jesus even experienced judgment, as we will, that’s how human he was. He, of course, was judged most worthy and alone merits* ‘sitting at the right hand of the Father’*.
Three days later we see how truly divine he is. Alleluia.