Minus (?) ratings for moves in game analysis

Now that I'm using game analysis more to my learning advantage, can someone either point me to a FAQ or explain what the minus values with certain moves mean? 

Ignoring for the moment my terrible play in this game, what do the -10.0, -15.2, and so on mean? The -M1 seems obvious, that I missed a mate, right? But even if that's right (is it?), the other values are a mystery to me. I acknowledge that this data may not be useful to someone at my level yet, but I'm still interested. Thanks!

Minus means that it's better for Black and plus means that it's better for White. And M1 is indeed a mate in one, M3 would be mate in three etc.

Ah! Okay, that makes sense, thank you. Any insight into the values themselves? Like, is -10 representative of... ten moves? Ten... points? I guess I'm just curious.

-10.0 in this case means that Black has an advantage which is comparable to having ten extra pawns on the board.

A plus sign indicates that White has the upper hand, while a minus sign indicates that Black has the upper hand.

The decimal figure indicates the equivalent number of pawns to which a player holds the advantage.

M1 just means that a mate in one is available on this current move.

Ah, a point is a pawn! Okay, that makes sense and is a good thing to know for the future. Honestly, though, I'm a ways from being able to apply that knowledge to my playing. But now I know. Thanks, @Suzki and @eric0022!

Note that those numbers are a measure of evaluation of the resulting position after the move or sequence of moves, not a measure of move quality itself.  If you're playing white and a move takes you from -15 to -4, that's a great move, notwithstanding that there's still a negative (black-favored) evaluation after the move.

+2.00 means white is better and -2.00 means black is better. If you are white, -2.00 probably means you missed a pawn and have a messed position. -10.00 means you have a really bad position with many missing pieces compared to black.