Lacrosse has elements of many sports depending on who you talk to: soccer, hockey, basketball, ... But the objective of the game is very simple. Place a rubber ball inside an opponent's goal more times than they do yours.
Although the objective is simple, the technical aspects of the game take time to learn. In addition, the rules are slightly different for boys and girls lacrosse.
The US Lacrosse Guidebook is the best resource that we've found to dive into the details.