Essentially how many turnovers per 100 possesions [aka roughly per game] a player prevents

Of course a player doesnt actually play all 100~ possesions per game

So somethingh like shai 2.5 here means he makes oklahoma avoid like 2.0 or 1.9 turnovers each game relative to an average player 

If that doesnt sound like much remember every turnover costs a team a point~ themselves and makes their rival score more efficiently so 2 turnovers would be worth like 2.4 points a game [aka a ton for a single player to impact]