What is WPA 2 encription & how would I install it?

Would this alleviate hijacking of outgoing info in a room where a stalker can see me reprogramming the router? If she sees me using a code/pword it would'nt do any good, would it? I suppose I could do it under a blanket or something, but if she has something that's reading my keystrokes she'd know it as soon as I typed it.