I am new and people keep saying things like ffa or other things what do they mean

ffa = free for all

GG = Good Game
WP = Well Played
WL = Warlight
GL = Good Luck
HF = Have Fun
FFA = Free For All
RT = Real Time
MD = Multi-Day

"gg" is also a common term to mean you surrender.

Here's some phrases used in titles:
vote 30min, direct 25h, auto 3d The boot times, in this example it means you can
vote to boot after 30 minutes of in-activeness, you can boot direct after 25 hours, and it bootsautomatically after 3 days.
RT, RD Random teams, random distribution.
2v2v2v2 In this example 4 teams of two players each.
FFA Free for all, e.g. no teams.
BBT Banking Boot Time

Moros.. that's a long title name..
I'd prefer

vtb30, db25h, ab3d, ffa5, MA

vote to boot 30 min, direct boot 25 hours, auto boot 3 days, free for all 5 players, multi attack

brb = I 'll be right back

g2g = I got to go

wtf = what the fuck
omg = oh my god
lmfao = laughing my fucking ass off
bff = best friends forever
ily = i love you

my favourite

ffs - for fu**'s sake

fiik
f*** if i know
afaik
as far as I know
idgaf
i don't give a f***

You forgot Umad (When someone goes mad :D)