There's a difficulty target that's needed to find a block. Kind of a "high score." Right now about 108,110,000,000,000. If you beat that target, you've found a hash that mines the block. So the best difficulty stat is your miner's score. M for million, G for billion, T for trillion. If it says 6.53G, your "score" is 6,530,000,000. Big number, but not high enough to catch a block.

That is EXTREMELY simplified, but enough to get the idea. Look at the live logs on your Bitaxe and you can see the difficulty numbers in near-real time. The target shown there is much lower in order to measure your work for payouts when mining to a pool like OCEAN or Braiins, so not really applicable to a solo pool. For solo, it's beat the high score or don't. All or nothing.