In the Commits tab you can see:

• in the upper part, the interactive Commits bar chart. It displays all commits made over the last year grouped by week. Each bar represents one week. Click a bar to see a total number of commits made that week. You can use arrow keys on your keyboard to navigate from one bar to another. When you click a bar or switch from one bar to another you see changes in the scatter chart below.

• in the lower part, the interactive Commits scatter chart. It displays detailed daily commit statistics of the week selected in the upper Commits bar chart. Each chart marker represents one day.