As the name implies, Main Point is the main surfing break in Arugam Bay. It's an intermediate wave best enjoyed by experienced surfers, but there's Baby Point and plain old swimming areas nearby.
Main Point is the closest point to Arugam Bay town and where you're most likely staying. To get there just get onto the beach and walk south. You can't really miss it.
The Point is great if you're a surfer, but also fun if you just want to watch people surf or hang out by the beach. The Main Point has intermediate waves which require some skill to surf, but just before that there's Baby Point which, as the name implies, offers gentler waves for beginners. Before that, depending on season, there are even calmer swells where regular people can swim.
Also right on the point is Mambo's - an extension of the Hikkaduwa franchise. This is a good hotel with pretty good food and cold beer. If you get one of the loungy seating area spots is also a great place to watch the surfers and people come and go.
Main Point is the most accessible surf spot in Arugam Bay and it has something for surfers, swimmers and loungers alike.
Start out at Baby Point, just before the Main. When it's time to chill (perhaps immediately), check out Mambo's. Good for sunsets.