I believe it is an association of former PC(USA) churches that rejected the PC(USA) heresy regarding Biblical marriage; amongst other issues.
Faith Presbyterian is just one local congregation, and is representative of its parent denomination, the Evangelical Presbyterian Church (EPC). The EPC is the second largest conservative Presbyterian denomination after the larger Presbyterian Church in America (PCA) and ahead of the smaller Orthodox Presbyterian Church (OPC). All three pulled away from the PCUSA (then PCUS) when the original body became heretical.