Dreams of being late are very common. In a survey of 1,181 Canadian university students, 59.5 % said they had ever dreamed of arriving too late, for example missing a train: the fifth most common of 55 typical dreams in that study. Women reported it a little more often (61.5 %) than men (54.5 %).
In the Typical Dreams Questionnaire study (Nielsen et al., 2003), "arriving too late, e.g., missing a train" ranked fifth of 55 themes at 59.5 %: 61.5 % of women and 54.5 % of men.
That number is how many people have ever had the dream, not how often it happens. The sample was young, mostly female Canadian psychology students, so other groups may differ.
What the theories say
The continuity hypothesis proposes that dreams draw on waking life (Schredl & Hofmann, 2003), so the deadlines of the day may turn up at night. It is a theory, tested mostly with dream diaries, not proof of why any one person dreams of missing a train.
What it does not mean
Dream dictionaries give lateness a fixed meaning. Research doesn't support one meaning per dream: what the studies show is how common a dream is and what it goes with in the people studied.
Questions
Is it normal to dream about being late?
Yes. About six in ten students in a large survey said they had ever dreamed of arriving too late.
Why do I dream about missing a train?
One theory, the continuity hypothesis, says dreams draw on waking life, including its deadlines. That's a theory, not a fact, and no study shows the dream predicts anything.
Sources
Nielsen, T. A., Zadra, A. L., Simard, V., Saucier, S., Stenstrom, P., Smith, C., & Kuiken, D. (2003). The typical dreams of Canadian university students. Dreaming, 13(4), 211–235. https://doi.org/10.1023/B:DREM.0000003144.40929.0b
Schredl, M., & Hofmann, F. (2003). Continuity between waking activities and dream activities. Consciousness and Cognition, 12(2), 298–308. https://doi.org/10.1016/S1053-8100(02)00072-7 (theory beat only)
73.8 %of students said they'd dreamed of falling
81.5 %said they'd been chased: the top dream of 55
18.8 %said they'd dreamed of losing their teeth