The Lord bless you for you honesty and your desire to know. Discernment of what is meant to be literal and what is symbolic, comes from becoming familiar with the book of Revelation by studying it and the related books and scriptures regarding end-time events. However, there is information that is made plain to the reader, the literacy of a thousands being one of them.
As I continue to proclaim, the book of Revelation should be read in the literal sense until a symbolic sense is obvious. An enormous dragon with seven heads should alert the reader immediately that a symbolic interpretation is required. The meaning behind the symbolisms are for the most part, revealed right in the Revelation itself. For example, the seven heads and the ten horns of the dragon, are revealed in Rev.17. The symbolism of the sun, moon and stars regarding the woman of Rev.12, is revealed in Genesis 37:9-10.
Just keep on praying about it and continue to read the book of Revelation and the Lord will reveal what is literal and what is symbolic.