הִנֵּה hinneh "look!" can serve a number of functions. In old translations it was often rendered "Lo!" or "Behold!" The important part this construction plays in giving the language of such Bibles a "biblical" flavor, illustrates its significance to Hebrew speech.

In narrative hinneh often marks a change in view-point: 

Ruth 2:4 where we are invited to "join" Ruth in watching Boaz' arrival;

Ruth 3:8, having followed Ruth to Boaz' feet, we share his surprised awakening. 

 

It also serves other functions:

affirmation (translated something like "indeed") - Ruth 3:2 (where the "look" seems redundant in English); 

explanation "that is..." (which we would put in brackets) Am 7:1; 

call to attention (Ruth 1:15)

marking events that happen contemporaneously - Ruth 4:1 where וְהִנֵּה suggests that hardly has Boaz sat down than the Goel arrives.