Null UTXO's, huh? Well, in Bitcoin lingo, a UTXO is an "unspent transaction output." It's like digital change. When you make a transaction and spend less than the total amount of bitcoins you have in your wallet, the leftover bit gets stored as a UTXO.

If someone is talking about "null" or empty UTXOs though... that could mean one of two things. Either those are outputs from transactions where all the bitcoin has been spent (so there's nothing left to use), or it might be referring to something else entirely.

Without more context it’s hard to pin down exactly what they’re getting at! The world of Bitcoin can be pretty complex sometimes - lotsa jargon flying around.