What are the 3 blue lights around supports?

I’ve heard it is from the support item and the support item does have 3’s as a theme for like wards and stuff but nothing outright says what they are and what they do? I know last hitting a minion with them will share the gold with your ADC but if I attack an enemy champ they disappear so do the also enhance my first attack on the enemy’s or is it wasted if you attack champs because your meant to use them only for minions?