trying to understand this mov memory[register] instruction

Windows 10, IDA Home, 64bit application compiled with Visual Studio.

I’m reverse engineering a crackme and i found this instruction :

  mov     cl, byte_51B000[eax]
  mov     byte_51B018[edx], cl 

in these 2 byte_ location are null terminated strings.

I’m not sure to understand exactly what it’s doing. Is it like an array index where byte_* is the array and [eax/edx] is the index ? i can’t find this kind of syntax anywhere, is it IDA specific ?