I believe that’s milli-bit-coins but not sure as the usual abbreviation is mBTC. This site was founded in 2016 but don’t you think they could take the time to update their sales pitch? This is an online lottery provider where the buy-in and winnings are “mBT”. Take /en/lotto – on their face menu they talk about their 12 different lotto choices to play (it’s actually 33).
Sometimes it’s hard to take some of these lotto sites seriously.