If the source register's value (in SRC1/dest) is not Zero, the location where the core will execute the next instruction is pointed to by the destination register (in SRC2). Prepare it in advance !
The Imm16 field can be used to XOR the source register with a sign-extended 16-bit immediate value, so the register can also be tested for inequality with a signed 16-bit value.
See also the other instructions of the JMP group : JMP, JZ, JO/JNE/JNO/JE, JS/JNS