This word contains the words 気 (energy) and 付ける (to attach). So, when you attach energy to something you're focusing in on it, right? This word is a sort of "order" as well, since it's te-form there at the end. It's a set phrase people say to other people who are doing dangerous things. It's kind of like saying "Attach energy to what you're doing! Stay focused!" A simpler way to translate this would be to say this word means be careful or take care, though. Learn this word so that you can always show that you're caring for your friends!
The readings come from the two words 気 and 付ける. So long as you know those from the previous levels, you should be able to read this one as well.
please be careful
to do something carefully
Please be careful of the fire on the stove.
It might rain today, so be careful and take a raincoat when you go out.
Be careful in big cities in this country, because there are many pickpockets.
It's not so bright around here, so watch your feet.