The speed of testing that type of hash.

If a website's data leaks, it's (hopefully) not storing your password in plain text but as a hash (a type of mathematical function that's easy to compute and hard to reverse). To check a possible password, you apply the hash function to it and then see if the result shows up in the stolen data.

Some hash functions are much faster to compute and others much slower, so this shows the number of hashes per second that can be computed in this setup (which if I'm reading correctly is a parallel arrangement of 480 GPUs).

Windows, at least in old versions (or when it needs to be compatible with old versions) used NTLM, which evidently can be attacked particularly quickly. If a bunch of hashes from KeePass are leaked, on the other hand, they can only be checked at about a millionth of the speed, so the same complexity of password would last a million times longer before being cracked.