Much is speculation because all has not been revealed to us, or we cannot comprehend it. Symbolic language (or analogy) is used.
The Catechism of the Catholic Church gives a few meanings of heaven, noting that** place i**s in quotes so it means *so called *place:
326 The Scriptural expression “heaven and earth” means all that exists, creation in its entirety. It also indicates the bond, deep within creation, that both unites heaven and earth and distinguishes the one from the other: “the earth” is the world of men, while “heaven” or “the heavens” can designate both the firmament and God’s own “place” - “our Father in heaven” and consequently the “heaven” too which is eschatological glory. Finally, “heaven” refers to the saints and the “place” of the spiritual creatures, the angels, who surround God. 186
186 Ps 115:16; 19:2; Mt 5:16.
1024 This perfect life with the Most Holy Trinity - this communion of life and love with the Trinity, with the Virgin Mary, the angels and all the blessed - is called “heaven.” Heaven is the ultimate end and fulfillment of the deepest human longings, the state of supreme, definitive happiness.
1035 The teaching of the Church affirms the existence of hell and its eternity. Immediately after death the souls of those who die in a state of mortal sin descend into hell, where they suffer the punishments of hell, "eternal fire."617 The chief punishment of hell is eternal separation from God, in whom alone man can possess the life and happiness for which he was created and for which he longs.