The white knight on a8 is not coming home. The two squares it could hop to, b6 and c7, are both covered by the black knight on d5, and the bishop on c6 already attacks it. So stop trying to rescue it and start charging for it.
7 
2 
f 
g The move is 1.Nxc7. Black recaptures with 1…Nxc7, and White has given a knight for a pawn rather than a knight for nothing. That piece is a desperado: doomed, and spent on purpose before the execution. The name carries a shrug. It is going anyway, so make it expensive.
The piece is dead, so spend it
Club players lose material twice in the same position. First the piece, then the pawn they could have eaten with it, because they burned four minutes hunting for a flight square that was never there.
The habit that fixes it takes ten seconds. The moment you see that a piece is trapped, stop looking at empty squares and look at occupied ones. List every square that piece can still reach that has an enemy man standing on it, take the dearest one, and let the recapture come. A knight for a pawn beats a knight for nothing, and often the pawn is a bishop.
The other common shape is a race. Your rook is attacked, his rook is attacked, and both are lost. Whoever captures first collects a pawn for free, so grab before you defend. That is how the exchange quietly changes hands in club games.
The desperado that saves the draw
There is a second sense of the word, and it wins half a point rather than a pawn. A piece that is lost anyway can go hunting the king instead of hunting material. A rook with nothing to lose starts checking on b8, a8, b8 again, and if the enemy king can never step off those files without walking back into a check, the game is drawn by repetition however much material you are down.
The stalemate version is even ruder. The doomed rook parks itself where it must be captured, the capture leaves the other side with no legal move, and a lost game turns into a draw.
Both versions come from the same thought: this piece has no future, so it has no fear either. If you want the pattern drilled in, trapped piece puzzles are full of it, and the position above is one of the friendlier ones.