How Jump instruction is executed based on value of Out- The Alu Output

Question

Figure from The Elements of Computer System (Nand2Tetris)

Have a look at the scenario where

 j1 = 1 (out < 0 )
 j2 = 0 (out          


        

Answer 1

If out < 0, the jump is executed if j1 = 1.

If out = 0, the jump is executed if j2 = 1.

If out > 0, the jump is executed if j3 = 1.

Hopefully now you can understand the table better. In particular, JNE is executed if out is non-zero, and is skipped if out is zero.