The Y Axis is the total number of items you’ve learned across all four different item types.
The X Axis is the date.
If you hover over the graph, you can see the number of items you’ve learned up to that date.
In the above figure, you can see that this user has learned 39 sounds, 29 components, 26 characters and 13 words by the date of Oct 8, 2023. The “total” indicates all of those items added up together. So in this case, this user learned a total of 107 items thus far.
You can filter out each item type by clicking on the legend above.
By filtering out, notice that the “total” amount changes to reflect which item types are left.