Using the conditional formatting command, you can quickly highlight the cells with the values above or below the average. Please check how to highlight values that are above the average, or follow the steps below to highlight cells with the values below the average:
Step 1: Select the data cells or range;
Step 2: Click the "Home" tab from the Ribbon;
Step 3: Click the "Conditional Formatting" command in the "Styles" section;
Step 4: Click the "Top/Bottom Rules" from the drop-down list, then select "Below Average" from the extended list;
Step 5: Format the numbers below the average, e.g., font and cell color;
Step 6: Click "OK" at the bottom and the numbers below the average will be in a different color.