The shortcut Alt+H, B is to add borders to the selected area.
Step 1: Select the data range you want to add borders;
Step 2: Press the Alt key, and you will see the access key on each tab;
Step 3: Click the letter H from the keyboard, and the Home tab will open;
Step 4: Click letter B to have the border options;
Step 5: Select letter A to have all borders.