To answer your question, it is both literal and symbolic. The phrase, "firstborn" can mean literally the "first one to be alive from the process of birthing." Of course, "death" is an abstract entity, so it's impossible for it to actually give birth. Thus, "firstborn" has to be used symbolically in this context to mean "preeminent one" or "foremost one." The "dead" part, however, is not symbolic, but literal. How do I know? Well, because the scriptures never indicate that Jesus spiritually died; he couldn't have, because he remained sinless to the end. However, the scriptures do indicate that he physically died... and by indicate, I mean they unequivocally say he died[e.g. John 19:18, Mark 15:39, Romans 6:8, Romans 6:10, Romans 14:9, Acts 2:23, Acts 5:30, 2 Corinthians 5:15, 1 Thessalonians 4:14].
Also, the context of Colossians 1:18 clearly hammers down the preeminence of Christ.
[Colossians 1:15-20] "He is the image of the invisible God, the firstborn of all creation. 16 For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things were created through him and for him. 17 And he is before all things, and in him all things hold together. 18 And he is the head of the body, the church. He is the beginning, the firstborn from the dead, that in everything he might be preeminent. 19 For in him all the fullness of God was pleased to dwell, 20 and through him to reconcile to himself all things, whether on earth or in heaven, making peace by the blood of his cross."
It's clear that by "firstborn from the dead" Paul means the "preeminent one" from the dead(those who are literally dead, not spiritually). Why? Because although Jesus died a literal death(as everyone else), he was also the first and foremost of many to be resurrected from death with an immortal, imperishable, spiritual body[e.g. 1 Corinthians 15:35-40, 1 Corinthians 15:42-45, 1 Corinthians 15:49, 1 Corinthians 15:51-53, Philippians 3:20-21, 1 Peter 3:18, ]. And because Jesus is the "preeminent one" born from the dead, our resurrection is directly tied to his.
[1 Peter 1:3-5] "3 Blessed be the God and Father of our Lord Jesus Christ! According to his great mercy, he has caused us to be born again to a living hope through the resurrection of Jesus Christ from the dead, 4 to an inheritance that is imperishable, undefiled, and unfading, kept in heaven for you, 5 who by God's power are being guarded through faith for a salvation ready to be revealed in the last time."
[Romans 6:5] "For if we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his."
And finally, the expression, "firstborn from the dead", occurs only once more at Revelation 1:5;
"...and from Jesus Christ, the faithful witness, the firstborn from the dead, and the ruler of the kings of the earth. To Him who loves us and has released us from our sins by His blood..."
This passage is very similar to Colossians 1:15-20. Colossians 1:16 mentions "thrones, dominions, rulers, and authorities" being created by Jesus; and here it mentions how Jesus is the "ruler of the kings of the Earth." It also calls Jesus the "firstborn from the dead" as Colossians 1:18 does. And finally, it mentions his blood, how he has "released us from the sins by his blood." At Colossians 1:20, it says that "through him to reconcile to himself all things... making peace by the blood of his cross." So, in both of the only two passages where "firstborn from the dead" is found, there is a mention of the blood of Jesus; this is indisputable a reference to the physical death of Jesus on the cross, of how his perfect blood was shed, and how that bought us back from sin and death.
Nothing in the context of Colossians 1:18 suggests that "firstborn from the dead" is a reference to his spiritual death(notwithstanding the fact that he never had one in the first place), and everything suggests that it is a reference to his actual death, i.e. the theme of the preeminence of Jesus and the mention of the blood of the cross. Both these things are also true of the only other place(in the entire Bible) where the exact phrase "firstborn from the dead" is found(at Revelation 1:5), where it also mentions his rulership over all the kings of the Earth, as well as how he released us from our sins from his shed blood.
I hope this helps! Have a great day. :)