I have no idea what this bar graph means, can someone help?

A bar graph is a chart that plots data using rectangular bars or columns (called bins) that represent the total amount of observations in the data for that category Bar graphs are commonly used in financial analysis for displaying data. A stock volume chart is a commonly used type of vertical bar graph.

Explanation:

Agroforestry is a collective name for land-use systems and technologies where woody perennials (trees, shrubs, palms, bamboos, etc.) are deliberately used on the same land-management units as agricultural crops and/or animals, in some form of spatial arrangement or temporal sequence.