Е-5

С ЧЕМ ЕГО (её, их) ЕДЯТ coll, humor VP 3rd pers pl with indef. refer, only used as a subord clause ( usu. after интересно, надо посмотреть, понять etc) or a question fixed WO

(one wonders, wants to know, understands etc) what the essential characteristics of the person or thing just mentioned are, or what the meaning of the word or phrase in question is: с чем его (ее) едят? - what is it?

what is he (she, it) (really) like? what sort of person (administrator etc) is he (she)? (in refer, to a device, machine etc) how (exactly) does it work? what (exactly) does it do (is it used for)? what's it for? (in refer, to a word or phrase) what does that mean?

я понял, с чем его (её) едят - I figured him (her, it) out

I got the hang of it I got a handle on it.

"У тебя есть модем?» - «А что это такое и с чем его едят?» "Do you have a modem?" "What's that, and what does it do?"