This is the 238th most frequent German word.
deshalb
"Deshalb" means "therefore" or "that is why."
Deshalb is conveying a consequence resulting from the situation mentioned in the first clause.
Es regnete den ganzen Tag, deshalb blieben wir zu Hause.
It rained all day, therefore we stayed at home.
Deshalb links the reason (train delay) to its outcome (arriving late).
Der Zug hatte Verspätung, deshalb kamen wir zu spät zum Treffen.
The train was delayed, therefore we were late to the meeting.
Deshalb is used here as a conjunctive adverb to introduce the cause-effect relationship between the two clauses.