Basically, it's an ideology that, much like Fascism, believes that the nation and the state should be one. Integralism, however, is explicitly Monarchist and advocates a kind of new-Feudalism, where regions are given a great deal of autonomy; the thought is that local autocrats would be more in touch with the people than far away politicians, and thus a country that purely expresses the will of the people would be created. The reality is probably less rosy, but we don't actually have an example of the ideology being tried, so you never know. Integralism also features an absolutist monarch who I believe has authority when he wants it but day to day running would be handled by local governors.
While Integralism is anti-semetic(probably; at least the leader of Brazil's Integralists was an anti-Semite) that's surprisingly the limit of their bigotry. As alluded to by the Brazilian focus tree, Integralism considers minorities to be important parts of the nation, and identifies an end to racial discrimination as an important step to ensuring the nation can be as strong as possible. While the Portuguese Integralist's anti-racism is not as explicit their focus tree also alludes to "benevolent imperialism" suggesting that the African clonies of Integralist powers would be integrated and their denizens theoretically granted equal rights. At the very least, given all the events surrounding native African terrorism in Mittelafrika being sponsored by Portugal, your average African perfers Portugal's Integralists to Goering, although this isn't saying much.