The numerical value you are referring to is called a statistic.
In statistics, a statistic is a characteristic or measure obtained by using the data values from a sample. The sample mean is a common example of a statistic, which provides a centralized value that summarizes a set of observations. Other examples of statistics include sample variance, sample median, and sample proportion. These values allow researchers to make inferences about a larger population based on observations from a smaller sample, using these calculated figures as summary indicators.