--+

The symbol --+ is a position evaluation. It says that Black's advantage is so large that traditional analysis treats the position as overwhelming. It is one level stronger than -+, which means a decisive Black advantage.

In Portable Game Notation, abbreviated PGN, evaluations can be stored as NAGs. NAG means Numeric Annotation Glyph, a numbered annotation code. A crushing Black advantage is NAG 21, written as $21 in the file. Software may display that code as --+ or with another equivalent visual symbol.

The symbol summarizes the judgment of an annotator or analysis tool; it is not the game result. It does not announce checkmate, compel resignation, or guarantee that Black will win, because mistakes and overlooked resources can still change the outcome.

The sign placement offers a reading aid: the plus is on the right, associated here with Black. The opposite symbol, +--, means a crushing White advantage.