Aggregation functions define the parameters of what we can do with the different data points inside one granularity chunk.
They’re used to calculate one “Daily” value (or whichever granularity we’ve selected) from all of the data items sent in this chunk (one day).
Just take a look at the previous example, and you can see the actual values for each granularity chunk below the data timeline.
After the first aggregation is applied, we still have multiple values (one for each granularity chunk), which is just enough information for a line graph. But if we want the output to be a single value (like on a “Number” datablock), we need to specify a second aggregation function that will aggregate all the granularity chunk values into one, as shown on the pink line in the example below.