This is the 1697th most frequent German word.
deswegen
"Deswegen" means "because of that" or "therefore."
In this sentence, 'deswegen' is used as a conjunction to indicate 'that's why' or 'therefore,' logically connecting the cause (didn't sleep well) with the effect (feeling tired).
Ich habe gestern nicht gut geschlafen, deswegen bin ich heute müde.
I didn't sleep well yesterday, that's why I am tired today.
Here, 'deswegen' illustrates a causal relationship between two events by correlating the rain with the decision to stay indoors.
Es regnet und deswegen bleiben wir zu Hause.
It's raining and for this reason we are staying at home.
In this context, 'deswegen' serves to explain the reason behind the event (the late arrival caused by the train delay).