Learn Russian: Она не предупредила нас о переносе, так что это её вина. - She didn't warn us about the postponement, so it is her fault.

Yes, they are very close in meaning. However, поэтому (therefore / that is why) is an adverb often used to start a new independent sentence, while так что (so / with the result that) is a conjunction that introduces a subordinate clause of consequence. Notice that так что directly follows the comma to link the result to the first action.

Why does предупредила take the preposition о here?

The verb предупредить (to warn or to notify) requires the preposition о or об plus the prepositional case to express what someone is being warned about. Here, she failed to warn us about the postponement, which translates as о переносе.

How is the word переносе constructed?

It is the prepositional case of перенос, meaning postponement, transfer, or shift. It is built from the prefix пере- (meaning across or re-) and the root from нести (to carry). Conceptually, it is the act of carrying an event over to a different time.

Since вина (fault) is feminine, why do we use the neuter это instead of эта?