How can a short circuit 'blow' a fuse?

Blowing Fuses

Fuses are designed and intended to protect electrical conductors [wires] from damage due to overheating resulting from too much current [measured in Amps] flowing through the wire(s).

A "short" circuit results in tremendously large amounts of current flowing through the conductors, which results almost instantly in generation of heat which can cause major damage to the wiring, AND be the ignition source for fire in the vehicle.

The fuse is nothing more than a tiny single strand wire sealed in a glass, plastic, or metal envelope [for safety], which melts, and thus, acting like an automatic switch, "opens" up the circuit when the current flow exceeds the capacity of the tiny wire. Most fuses do this almost instantly, although there are "slow blow" fuses designed to allow small, short term overloads.