Revelation 20:10 And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever.
Revelation is a book of symbols.
The lake of fire represents the ‘second death’ which is total destruction.
Revelation 20:14 And death and hell were cast into the lake of fire. This is the second death.
Revelation 21:8 But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the lake which burneth with fire and brimstone: which is the second death.
The ‘devil’ in the New Testament represents the propensity to sin within man. During the millennial reign of Christ, sin is restrained by his government, because criminals will have no hiding place. At the end of this time the government is relaxed to permit a final rebellion of the wicked prior to the second resurrection and final judgment.
The beast represents man’s political government which will be destroyed at the beginning of Christ’s millennial reign.
The false prophet represents apostate Christianity which will likewise be destroyed at the beginning of Christ’s millennial reign.
Man’s political government, apostate Christianity, and the proclivity to sin within man, cannot be literally ‘tormented day and night forever’ so the description must denote that they will never again be released into the earth.
From that time forward, God’s glory will fill the earth.
God’s people will possess the divine nature and God will live in and with them forever.
I hope you find this helpful.