It originated from the definition "Laughing out loud" or LOL (also written occasionally as "Lots of Laughs"), used as a brief acronym to denote great amusement in chat conversations.
Now, it is overused to the point where really nobody laughs out loud when they say it. In fact, they probably don't even give a shit about what you just wrote.
ALOL just emphasize the meaning of LOL but better. Actually laughing out loud.
Candice: its my first time and I loved it!
Candy Box: lol
Candice: I hope I can be like you one day!
Candy Box: ALOL
Candice: Why are you Actually Laughing Out Loud???
Jack Hammer: Dude what size are you? I'm a 4.
Six-Pack Muscle: ALOL
Jack Hammer: Whats so funny???
Six-Pack Muscle: You need double than that. ALOL