The changes you make on this panel are tiny but can have a cumulatively big impact on your daily typing routine. The options have been organized on two panes: Keyboard and Keyboard Shortcuts.
On this pane, you have these choices:
Key Repeat Rate, Delay Until Repeat. In Mavericks, holding down letter and number keys no longer makes them repeat, much to the disappointment of people who like to type, for example, “AAAAAARRRRRRGGGGHHH!” Instead, holding down a key produces a palette of alternative accented versions of that letter, like é, è, ê, ë, and so on.
Only the punctuation keys still repeat, so at least you can still type ****** or ????? or !!!!!!!.
There are sneaky ways to make your regular keys repeat, as they did in days gone by; see Power Typing. In the meantime, these two sliders govern the repeating behavior of the punctuation keys. On the right: a slider that determines how long you must hold down a key before it starts repeating (to prevent triggering repetitions accidentally). On the left: a slider that governs how fast each key spits out characters once the spitting has begun.
Use all F1, F2, etc. keys as standard function keys. This option appears only on laptops and aluminum-keyboard Macs. It’s complicated, so read One-App Exposé slowly.
Adjust keyboard brightness in low light. This setting appears only if your Mac’s keyboard does, in fact, light up when you’re working in the dark—a showy feature of many Mac laptops. You can specify that you want the ...