The Record Navigation buttons are found at the bottom right side of several forms and are used to move from one record to another. It also displays how many records are in the current form and what record you are currently on. Clicking on one of the four buttons will navigate you through your existing data.
If the first 2 buttons are disabled then that means you are on the first record and cannot move back any further. If the last 2 buttons are disabled then that means you are on the last record and cannot move forward any further.
You can also move to a specific record number by typing in the record number you want and pressing Enter.