It’s a Bank of America offer of up to 90,000 bonus miles for a card that earns 1.5 miles per dollar on all of your spend. I’d stop at earning 75,000 bonus miles, but if you go all the way you’ll earn 127,500 miles including the miles from your spending.
Virgin Atlantic miles aren’t the best miles, but this is a great bonus from a bank you may not already have any rewards cards from.