The figures amount to this : admitted on Friday, deaths 8 in a 1,000. Admitted on Monday , deaths 5 in a 1,000. This has been well covered all day on the news here. The figure is statistically significant because it is repeated; it's not much of a consolation that you have only a very small chance of dying , whatever your admission day.
Various reasons have been suggested, including that the patients differ in some way on Fridays (!), but it seems to be a lack of staff , specialists, and full facilities at weekends, the 48 hours after Friday.