There are two interpretations: (1) the ten days represent something that we don't know about. So the meaning is “real” it's just that we don't know the context. (2) the great NT scholar William Ramsay says that it is a period which can be measured and that it will come to an end. The persecuted church “will live through it and survive, and has therefore no reason to be afraid of it.” Ramsay adds that it must be taken in a figurative or symbolic sense.
I take the first interpretation and meaning. We just don't know what the ten days are about but the period is real. When numbers, names, or figures of speech are given this usually means that they represent something that is actual and was known by the recipients. Actual numbers, names, or figures, when given, had to do with something that was known.
This ten days would be terrible for John goes on and says: “be faithful until death,” implying that some may die during this time. But John then adds that Christ says: “I will give you the crown of life.” This crown could be the same mentioned in 3:11: there is an hour of testing that would come upon the whole world (v. 10), “to test those who dwell upon the earth.” “But no one can take your crown” (v. 11). That is, you will not lose your eternal life.
What is said to one church is applicable to all churches and the believers who are the congregation and assembly. If this is salvation, all believers will be blessed with this fact of an unending life of blessing.
Thanks for asking.
Dr. Mal Couch (7/12)