heard: i.e. while he was at Ephratah. David"s father was an Ephrathite (of Bethlehem-Ephratah. Compare Genesis 35:19. David had "heard" of it as being in Shiloh.
it: i.e. the Ark. in the fields of the wood. at Jaar's fields: i.e. Kirjath-jearim (1 Chronicles 13:5.)