What does general admission (GA) mean?

I'm going to see 5sos in Boston at the Brighton Music Hall in 6 days and I was wondering what GA means? I know its a really small venue with capacity of like 400 and its an acoustic show. I was checking the "My Tickets" section on ticketmaster.com on my iphone and it says Section/Aisle & Row/Box & Seat but it only says "GA" under Section/Aisle which i'm guessing means general admission. I googled pictures of the venue and it didn't look like it had seats but i'm not sure. So does that mean like I can stand anywhere? Like first come, first serve. The ealier you are the closer up front you get? Thanks so much if you answer and please respond quickly the show is in 6 days! <3:)

If it's standing, it means that the location you'll be will depend on what time you get to the venue. If there's seating, it'll be on a first come, first served basis.