In this very short scene, Antonio erroneously reports to his brother Leonato that Don Pedro is in love with Hero and will approach both her and Leonato at the coming dance. Leonato asks Antonio to tell Hero about it.
Here is the result of the first incident of overhearing or noting. Antonio's man who overheard the final conversation of the first scene — between Don Pedro and Claudio — did not understand that Don Pedro would be speaking to Hero and her father on behalf of Claudio rather than for himself. Thus, the stage is set for a misunderstanding: Don Pedro's masked wooing of Hero is likely to be misinterpreted by Hero because Antonio will have told her that Don Pedro desires her for himself.
Borachio overheard the same conversation and will report it to his master, Don John, in the next scene.
Although the first line of this scene refers to Antonio's son, Hero is later declared to be the sole heir of both Antonio and Leonato (Act V, Scene 1). The present version of the play is the product of several revisions by Shakespeare as well as by his first editors and publishers. In one version, Antonio's son appeared in this scene with a musician. He was edited out of the scene but is still referred to incidentally here, although later he doesn't exist at all.