In this sentence, "law books" is being used as a nickname. (My guess is that the person being called "law books" is studying to become a lawyer or working hard at their job as a lawyer). The stress is slightly more on "law"

Thank you Michael.

It is a compound noun ; in this case. two nouns working together. The "books" - the last noun - typically carries the main meaning, and the first noun modifies or restricts it. Here, this is being used symbolically, obviously - the remarks are addressed to people, not to books. Emphasis in English can be tricky for learners, in that speakers often move the emphasis around to affect their meaning. This phrase ("law books") is just (to my ear) an affectionate little form of address for a group of people studying or researching together (using law resources). The natural emphasis would normally be fairly even between the two words, with just a little more on the "books". Both are relatively unstressed in the sentence, which I would read : ("stressed +" is more than "stressed" is more than "mildly stressed") : Hey (stressed +) law (unstressed) books (unstressed), read (stressed +) y (unstressed) for (unstressed) a (unstressed) lit (stressed) tle (unstressed) fif (stressed + ) teen (unstressed) min (unstressed) ute (unstressed) re (stressed +) cess (mildly stressed)? If the speaker is making this a question, as it reads, then the pitch will hold about level on re - cess. or even rise slightly. If it is really an exclamation, as punctuated, we'd expect a "down ending" - pitch falls slightly from re to cess. This might be of interest : https://www.fluentu.com/blog/english/english-intonation/