This is a hint that they will give away their heart after nine days, because they have written and sent four or five couplets of Bedil in their letter.

Here, the poet playfully decodes a secret message in his beloved's letter. By sending four or five couplets by the master poet Bedil, she leaves a witty clue: four plus five equals nine, meaning she might finally yield her heart in nine days. There is also a delightful pun on the name 'Bedil' (which literally means 'heartless' or 'one without a heart'), teasing that the lover who claimed to have no heart is now gently preparing to surrender it.