haha...... just in case anyone is still confused.......... power outlet is the port in ur wall which lets u enter a plug and gives power (electricity). its also called socket. and ac adapter is the big white 'plug' of ur mbp.
battery indicator is on the upper right corner of ur screen (shows a battery sign). it shows the remaining battery power in residual time or percentage, as u like.
u can also check the battery by pressing a small white round button on the left side of the mbp. it shows the battery by 8 indicator lights, where lighting 8 of them means full battery and blinking 1 means almost no battery. u can check it anytime, even the laptop is switched off.