The 'Frontpage' or 'Home' page is the first page you see upon entering your SMF/Tinyportal site. You have many different options to design the frontpage the way you like it best: set it up to show panels & blocks, include (featured) articles and/or forum topics - or a whole single page.
The use of the frontpage is optional: if you don't really need it you can set Tinyportal up to go directly to the forum. You can find the frontpage settings via menu option"Tinyportal > Settings > Frontpage". To learn more about it's options, please read: Frontpage Settings.
See below two examples of frontpages to give an impression what a Frontpage can bring to your forum.