legend / key
legend / key (leyenda / clave)
the box on a graph or map that tells what each color, line or symbol stands for.
Example
The key shows that blue bars are 2023 and gray bars are 2024. (Read the key before comparing the bars.)
In Spanish
legend / key (leyenda / clave) — el recuadro de una gráfica o un mapa que indica qué representa cada color, línea o símbolo.
The key shows that blue bars are 2023 and gray bars are 2024. (Lee la leyenda antes de comparar las barras.)