Not able to understand this peice of code can anyone help me with it?

    self.backbone = timm.create_model(backbone, pretrained=pretrained)
    self.in_features = self.backbone.head.in_features
    self.backbone.reset_classifier(0)
    self.fc = nn.Linear(self.in_features, num_classes)

Also How do we connect a backbone model and embedding model?

backbone model is swin_large_patch4_window12_384_in22k