In probability/statistics this is the “normal distribution” function. it is a function, so there is not one answer (what it equals to). it is used for things like estimating how much of a data set is above or below a certain value, or within a certain range for data sets where the distribution is not known, and based on statistics and probability theory there are certain indicators that tell us whether or not this function will give us accurate estimates. probably the most common use would be using it to determine the proportion of the values that fall within a specified number of standard deviations from the mean. If you ever had a statistics class and had to use those tables for finding Z values, that is related to this function. the answers would be like either percentages or inequality statements with percentages.