Some of the law changes from the International Football Association Board are quite trivial but several could make a big difference to the game. They revolve around drop balls, handball, goal-kicks, free-kicks, penalties and substitutions.
A full outline can be found in this interesting article from the BBC website -
https://www.bbc.co.uk/sport/football/48382254
or visit http://www.theifab.com/news/laws-of-the-game-201920-coming-into-force-1-june-mobile-application