Or if you prefer to break it down to circuit building blocks you *SHOULD* recognize:
U1, M1 & R2 are a classic OPAMP + MOSFET current sink, with its control voltage from the drop across the load current shunt R1
==> Id(M1)=(R1/R2)*Iload
U2, R4 is simply an inverting current to voltage convertor, referenced to 0V rather than the negative supply.
==> Vout=-Iin*R4
Putting it all together,
Vout=(R4/R2)*R1*Iload
Note that if M1 drain ever gets disconnected, or if U2 rails due to excessive load current (or poor choice of resistor ratio), U1 will rail, putting close to its full V+ supply on the MOSFET gate. That's 17V, and the 7N2002 max Vgs is +/-20V. If you were using >5V positive rail U1 would need to be powered between 0V and the negative rail to limit the max Vgs. If you wanted to monitor a -24V rail you'd need a separate (positive) regulator to supply U1 with 12V or 15V, referenced to the negative rail and fed from the 0V rail. e.g. LM78L12 or ..L15 or a Zener and a dropper resistor.
Also, in all cases it would be advisable to add a clamping diode from 0V to U2 In- to prevent it being dragged too far below ground during over-current faults. 1N4148 should do nicely. A resistor in series with M1 drain to limit the fault current through the clamping diode may also be necessary, chosen to still leave enough voltage across M1 for linear operation at full scale current.