2 Samuel 17:19 Meaning

17Now Jonathan and Ahimaaz stayed by En-rogel; for they might not be seen to come into the city: and a wench went and told them; and they went and told king David.

18Nevertheless a lad saw them, and told Absalom: but they went both of them away quickly, and came to a man's house in Bahurim, which had a well in his court; whither they went down.

19And the woman took and spread a covering over the well's mouth, and spread ground corn thereon; and the thing was not known.

20And when Absalom's servants came to the woman to the house, they said, Where is Ahimaaz and Jonathan? And the woman said unto them, They be gone over the brook of water. And when they had sought and could not find them, they returned to Jerusalem.

21And it came to pass, after they were departed, that they came up out of the well, and went and told king David, and said unto David, Arise, and pass quickly over the water: for thus hath Ahithophel counselled against you.