Excel will show the data point values when you hover over on chart (e.g., series, point, value), but if you accidentally hide this on your computer and you want it back, please follow the steps below:
Step 1: Click the "File" Tab from the ribbon;
Step 2: Click "Options" from the left navigation menu;
Step 3: Click "Advanced" from the left navigation menu in the dialog box;
Step 4: Check "Show data point values on hover" under the section of "Chart";
Step 5: Click "OK" at the bottom to apply the changes.