How to understand it
Give the dream a title, then list three personal associations. A train may remind one person of family visits and another of missed deadlines. Neither association is a universal dictionary definition.
An example
If a dream is upsetting, ground yourself in the present before analyzing it. Repeated distress that affects sleep is a reason to seek appropriate support, not to search for an omen.
Use it carefully
Compare entries over time only if it helps. A recurring image might point to a recurring concern, or it might be a familiar story your mind reuses.
Try a reflection
Which detail feels most vivid, and what does it connect to in your life?