+--

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

In Portable Game Notation, abbreviated PGN, evaluations can be stored as NAGs. NAG means Numeric Annotation Glyph, a numbered annotation code. A crushing White advantage is NAG 20, written as $20 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 White will win, because mistakes and overlooked defenses can still change the outcome.

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