If you are asking about the worksheet tabs:
A worksheet can be either fill the Excel workspace (the workbook name will
show on the title bar above the Ribbon), or as an object within the
workspace (the workbook name is displayed on the worksheet title bar below
the Ribbon)
In the second case the worksheet can be move around and resized. This can
result in the worksheet tabs being hidden. On the title bar below the Ribbon
click the middle of the three icons to the far right -the Restore/Maximize
button. Now the worksheet occupies all the workspaces and tabs are visible
OR, it the worksheet is maximized:
Office button (pretty round icon on left of Ribbon)
Excel Options button in bottom of dialog
Advance tab in left side
Down to "Display Options for this Workbook"
Third item down "Show Sheet Tabs"
best wishes