Flags also shown when hovering over that field - and I know that is of no use to an iPad!
Possibly. When you say failed do you mean that the overall SMART health status (first line on screen) was not a PASS? That's the disk firmware's overall assessment although it often gets it wrong.
Your disk has had a very large number of sector reallocations - a number above the threshold that the manufacturer indicated as normal hence the 'Failing now'. However, these could have all happened early in the disk's life due to a manufacturing defect and they have now been reallocated so everything's fine, or they could have occurred recently due degradation in an area of a platter... no way to tell without historical data.
Keep an eye on the number and if it isn't growing over the course of a week then you're probably fine.