I assume this is a fancy new contraption running Leopard? If so, the f10, f11 and f12 keys do strange stuff. Bringing up the Dashboard for instance. I susepct you will have to go into System Preferences (you can find that in the Dock or the Apple menu top left of screen) and undo whatever you did to cause the strange box outlines and commentary. I can't be more helpful than that since I have never seen the things you describe and my antique Mac runs Tiger.
NEED SOME HELP WITH MY MAC

hi guys I just got a mac and have done some system adjustments- but now strange box outlines appear round objects, and the computer voice is commentating on everything. My f10 f11 and f12 buttons also dont function as sound adjustments, but in moving between windows. I know this isnt the right place for it, but i was hoping to get some help.....
If you think your Macintosh is malfunctioning or damaged, you could try asking a question on iFixit and get a relevant answer. If I had to guess what happened, though, you may have turned on some kind of accessibility feature, like ChromeVox on Chrome OS (enabled by pressing Ctrl+Alt+Z or in the Accessibility settings). Perhaps try searching the settings for an option to disable whatever function was enabled and rearrange the function keys.
hi guys I just got a mac and have done some system adjustments- but now strange box outlines appear round objects, and the computer voice is commentating on everything. My f10 f11 and f12 buttons also dont function as sound adjustments, but in moving between windows. I know this isnt the right place for it, but i was hoping to get some help.....