That is the difficulty, a bit of a strange metric imo. Multiply that number by 2^48 and divide it by 65535 to get the expected number of hashes needed to mine a block. The word "expected" is very important though, as it could also take just a single hash to find a valid block.

It makes more sense when you look at the hashrate, currently around 500 EH/s or 5•10^20 hashes/s. Multiply that by 10 minutes (600 seconds) and you’ll get pretty close to the same number:
~300 sextillion 

 Yeah, it doesn’t mean you need that exact number of hashes to guarantee a new block. A single 100Th ASIC can already do 1 trillion calculations per second.