What does 1 Chronicles 21:12 mean?

'Three years of famine, or three months of being crushed by your enemies while they chase you, or three days of the Lord’s sword—plague in the land, with the Lord’s angel bringing destruction everywhere in Israel.' Now decide what answer I should take back to the one who sent me.' 1 Chronicles 21:12 - Modern Text Bible

(Gad lays out the three options: famine, war, or plague, each with serious consequences for the nation.)