"Revelation 5:13 What it mean"

The preposition phrase "under the earth" is used three times in the New testament, it is used in Philippians 2:10, Revelation 5:3, and Revelation 5:13. Paul writes, "That at the name of Jesus every knee should bow, of things in heaven and things in earth, and under earth Phil. 2:10. John is recording his  vision in the book of Revelation when he writes," And no man in heaven, nor in earth, neither under earth, was able to open the book, neither to look thereon" in revelation 5:3 and verse 13 he writes, "and every creature which is in heaven, and on the earrh, and that are in them, heard saying! Blessing and honor and glory and power, be unto him that sitteth upon the throne, and  unto the Lamb for ever and ever"

First. We should note that the expression "under the  earth" is used in these passage in relationship to the expression "in heaven", and "on earth" the basic idea of these three expression being used together is completeness. It indicates that there is not a single location where exist a person of any kind whether (Angel, man or demons). That will not participate in the event being describes in this verses. In other words it is  a rhetorical way to express an absolute and that is- how we should generally regard  the  whole of the expression, "in heaven, on eartb, or under the earth. 

Second. We also note that just as there are person in heaven such as Angel, and person on the earth such as man, there are also person" under the earth."consider the language used to describe Jesus' journey of the death (Ephesian 4:9-10) "Now that he ascended what is it and that he also descended first into the lower part of the earth? He that descended is the same also that Ascended up far above all heavens that he might fill all things." Jesus descent unto the "Lower parts of the earth." has referenced to His journey to Hades after His death on the cross. In (acts 2:27). Peter qoutes from Psalm 16:10, because thou wilt not leave my soul unto Hades, neither with thou give they Holy one to see corruption he explain that this is referring to Jesus when He says in (verse31). He be forseeing this spake of the resurrection of the Christ that neither was be left untio Hades, nor did his flesh see corruption. "we can conclude from the coupling of these verses together that Hades is the unseem realm "under the earth" Jesus gives us a picture of the Hadean rralm when he tells the story of the Rich Man and Lazarus in (Luke 16:19-31) . Both were in Hades the unseem realm The rich man was in torments, Lazarus was in the paradise to put it simply, paradise is the place where the wicked go after dead, Jesus told the thief on the cross. "To-day shalt thou be  wilt me in paradise (Luke 24:43). These are all places  thatvare" under the Earth." hence, both the sainted dead and the wicked are. "under the Earth" and all are awaiting the Day of Judgment when everyone will come forth from the grave. Jesus said, "Marvel not at this for the hour is coming, in which all that are in the grave shall hear His voice and shall come forth they that have done good. Unto the resurrection of life, and they that have done evil, unto the resurrection of damnation." so as i understand it, the expression." under the earth" refers to any one who is awaiting the resurrection of the dead; both righteous awaiting the resurrection of the dead; both righteous and unrighteous.