Yes, this is assembly.
0000001f test eax,eax
00000021 je 0000000000000028
test eax,eax checks if eax register is zero.
If this is the case it jump to address 0x28. (
je is jump equal), skipping the next call.
If it is not zero it does not skip the next call.
Regardless of that it then continues at 00000028 with
cmp qword ptr [rsp+48h],0
All of this by someone who has not used i386 assembly in 15 years and who had to google for hits like these.
(Which is my polite way of saying: "Please do some research before asking").
Is this assembly language specific to the processor?
Assembly is specific to a processor range/family.
E.g. this one would work on an AMD opteron, AMD K6, K7, intel celeron, intel core, ... (all i386-ish code)
While things like this would work on a 6502, a 6510 and similar:
If yes, do developers generally use this for debugging?
I assume most do not. I assume the average dev. does not even know what assemble or machine code is. Nor has (s)he any idea about address busses, data busses, cache lines, memory architecture or anything 'deep'.
However some of us do.
The only assembly language I have learned was for 8085, which I don't remember anymore.
That was a precursor to the code you used in the example.