By default, whenever you open the Excel, the vertical scroll bar appears on the right which allows you to view more contents at the bottom.
If it disappears, you need to follow the steps below to bring it back:
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 vertical scroll bar" under the section of "Display options for this workbook";
Step 5: Click "OK" at the bottom to apply the changes.