The best is to just play with them. Open the properties box so you can see
what's going on. Now open the toolbox and click / drop a tab control on a
blank form. On my version of Access, the tab control is in the middle
column, second row from the bottom. Hover the mouse over it and it should
say "Tab Control."
You'll note a couple of things. There are individual tabbed "pages" (two by
default, but you can add more) --- and each has a control name. Click on
each tab to see its properties. You can set the name of each tab control as
one thing, and the wording that actually appears on the tab (Caption) as
something else --- they start out the same.
And the whole thing has a control name itself (click on the very edge of the
set of tabs to show its properties). One of the properties of the "while
thing" is how the tabs look --- whether they are "standard tabs" or buttons,
etc., whether it can exceed a single row of tabs or go onto multiple rows,
etc.
Of course, you can have controls on the form that are not on the tab ---
just on the detail section of the form itself. These will be available
regardless of which tab is selected (global to the form).
When you play with it for a while, you'll get the hang of it. Then you can
fancy it up with colors, etc.