Nice to see you on the BG forum rickroll.
This site is a little dated but has a thorough glossary.
Here are some terms from this thread --
Gammon
A completed game of backgammon in which the losing player has not borne off any checkers. A gammon is also called a double game because the winner receives twice the value of the doubling cube.
Take Point
The minimum game winning chances at which it is correct for a player to accept a double; the point at which a player is equally well off accepting a double or refusing a double; a player's drop point.
Dance
[From the action a player makes as he first reaches to enter his checker then pulls his arm back when he notices the numbers are blocked.] To throw numbers which fail to enter a checker from the bar.
Crunch
The forced evacuation of desirable points (2) due to the lack of alternate plays; in particular, a position in which you are forced to bury checkers deep within your home board.
"Killing gammons" isn't on there, but the idea is that (in the position I screenshotted) he only needs 2 points to win, so if I double to 2 he doesn't benefit from winning a gammon (which would give him 4 points, overkill since he only needs 2). On the other hand I need 4 points to win, so with the cube on 2 a gammon (again, 4 points) would be very good for me.
The numbers associated with an error (e.g., 0.110) are a measure of how bad the error is. It's related to how many points of EV your move gives up compared to the best one (though in matches it's a little bit more complicated). The higher the number the worse the error. 0.110 is a pretty bad error (a blunder), and 0.575 is an enormous blunder.