Answer:
1. What emotions does it create?
2. What ideas and images are connected to it?
3. Is there an object or idea with significance beyond its literal?
Explanation:
A symbol is a word or expression that means something else than its literal meaning. For example, in its literal meaning, a dove is a bird; however, its symbolism is that it represents purity and freedom.
If you want to know what a symbol means, then you need to see what feelings it evokes in you (sad, happy, angry, etc.), the images that are related to it and might help you understand the symbol further, and to check whether or not there is a symbol at all apart from the literal meaning of the word.