> What is numeric value 2.01

In general, a 1.00 value means "a pawn up", so 2.00 would mean "2 pawns up", the .01 would stand as "2 pawns and 1 centipawn better". These terms may not be taken literally, as in, dynamical factors are taken into account, if you don't see a pawn advantage anywhere, a 1.00 score would mean "the dynamical factors of the position are worth a pawn advantage".

Rybka actually doesn't do this, her score shown is expected outcome. A 0.00 score means "50% expected performance", like, after playing this game it is expected to be drawn, or if it's won by white, the next time on the same position black is expected to win, etc.

The higher the score, the higher the expected outcome (eventually reaching 100%, meaning "the side playing this move is expected to win all the time", though due to mis-evaluations such high scores could be shown for drawn games...)

> what is depth 12 indicate please.

It means how many halfmoves has the engine searched (a move is 1.e4 e5, a half move is just e4). In reality, engines tend to reduce some lines and extend others, so this concept becomes blurry. Engines like Rybka obfuscate this number, so that some times she actually searched 4 half moves more than she shows, and engines like Stockfish just increase this number every iteration, regardless of halfmoves analyzed.

Basically you can ignore the value of this number, what only matters is that a move shown at depth 15 has some 16.7% chance more of being the best move than a move shown at depth 14 (simply put, the higher this number, the better the expected move).

> Also, I see at bottom, 7 book moves. How can I use these to determine stong reply?

You can't, that's the PV, it's the line that the engine looked and deemed best, from where the score you see comes from (the 2.01 you see comes from the end of the variation).

Huh, my intention wasn't to help with that...