'Anticipatory breach' means a breach that occurs before performance is actually due. An anticipatory breach occurs either when a party indicates in advance that they will not perform when performance becomes due (i.e. they repudiate their obligations), or when they fail to do what is necessary to prepare for performance so that it is obvious in advance that a breach will occur.
In either case, the non-defaulting party is entitled to 'accept the defaulting party's repudiation' and sue immediately for breach of contract.