Is there anyone left in the world who is interested in Overwatch, but hasn't yet tried it? If so, you'll have (another) opportunity to dip your toes in the water next weekend, when it once again goes free for everyone.
The free weekend will include all Overwatch heroes, including the Hammer (which is what I'm going to keep calling him until someone makes me stop), and 18 maps in Quick Play, Custom Games, and the Arcade. Loot boxes will be earned, levels will be upped, and any progress you make will carry over into the full game if you should choose to buy it.
It's all fairly standard stuff for an Overwatch freebie, with the one exception that this time around it's exclusive to the PC for some reason. You will of course need a BattleNet account to take part in the freebie, which you can pick up here.
The Overwatch free weekend begins at 11 am PT on July 26 and ends at 11:59 pm PT on July 30. Time zone conversions and other such details are available at playoverwatch.com.