A histogram is a type of graph, usually using bars to indicate the measurements of the several variables being measured and recorded on the chart. If the variables being measured are listed along the bottom horizontal axis of the graph, the increasing values or amounts of the variables would be listed at evenly spaced intervals along the vertical sides of the graph. Interpretation of the information on the histogram would then require observing the vertical height of the bar indicating the value for each variable.
In the situation you have been given, the last three bars are of approximately equal height. This would mean that the final three intervals, or variables, being measured in your histogram are all of approximately equal value.