What appeared to be a sea of glass: see 4.6.

Mingled with fire: it is impossible to know precisely what the writer is describing. Perhaps flashes of light, like lightning, were being reflected on the surface of what seemed to be a sea of glass, or crystal. Or it may have been that the sea was red in color.

Conquered the beast and its image and the number of its name: for conquered see 2.7; 6.2. The construction of the Greek text makes it appear that the conquerors had conquered three things: (1) the beast, (2) its image (or, statue), and (3) the number of its name. But all three refer to the same one, that is, the first beast, who came up out of the sea (13.1), in whose honor a statue was built, which people were ordered to worship (13.14-15), and whose name was represented by a number (13.16-17). To avoid giving the idea of three different things, perhaps something like the following can be said: “I also saw those who had defeated the beast and its statue, that beast whose name is represented by a number.” This may be better than saying they had conquered a number. Bible en français courant has “they had won the victory over the beast, over its image, and over the number that corresponds to his name.” The meaning of the statement is the same as what is said of the redeemed in 14.4-5: they had remained faithful to Jesus Christ and had not worshiped the beast.

Harps of God: that is, harps given to them by God. For harps see 5.8.

Quoted with permission from Bratcher, Robert G. and Hatton, Howard A. A Handbook on The Revelation to John. (UBS Handbook Series). New York: UBS, 1993. For this and other handbooks for translators see here .