It's going to be a relatively minor setback. Biggest issue will be pad repair time. Starships is still in development and has been going boom pretty regularly, though not before launch usually! The investigation of the cause will be interesting. Given the current political context it's probably going to be AMOS-6 ramped up exponentially.

AMOS-6 was a pretty similar situation where a rocket exploded prior to a static-fire, and in fact is the reason that static fires are done without payloads, though Starship would not yet have a payload. The difficult to explain nature of the explosion, alongside some quite compelling circumstantial evidence, caused a theory of sabotage (sniping an exact segment of the rocket) to become widespread. Of course the cause here could be more straight forward to pin down - we'll know a lot more in a few days!