What does OVERLOAD mean? What resistance value is on the Ohmmeter

if the positive probe is connected to the anode of a diode, a finite resistance value is displayed. What value of Resistance does this represent?
And if the leads are reversed the DMM typically shows an “Overload”( OL) reading. What does that mean?

That is the forward resistance under one set of conditions, ie, the current generated by the ohmmeter.

When it reads overload, it means the resistance, in reverse, is too high for the meter to measure.

Digital ohmmeter cannot show good test on diode unless it has a special " diode test " selection. Then it shows about 0.5V and has a short beep tune while doing forward bias test.
But most analogy type ohmmeter shows a few kilo ohm while doing forward bias test on diode, and infinite ohm while reversing the probes. That tell the diode under test is a good diode.

"Overload" or "Overflow" on a DMM means that the scale is exceeded.
A typical (economy) DMM has 20 meg Ohms internal resistance.
On resistance scale: "OF" or "OL" represents "In excess of 20 megs-
(but not necessarily infinity"
Resistance readings on diodes are difficult to interpret.
Your DMM has a diode check feature which directly reads
forward voltage drop.
(As 26Leeloo pointed out).