history=model.fit(x_train, y_train,epochs=epoch,validation_data=(x_test, y_test), callbacks=[reduce_LR])

This code snippet trains a machine learning model using the fit method of the model object. The training data is passed as x_train and y_train, and the number of epochs to train the model is specified by the variable epoch. The validation data is passed as x_test and y_test.

Additionally, a callback function named reduce_LR is passed as an argument to the fit method. This callback function will reduce the learning rate of the model if the validation loss does not improve for a certain number of epochs.

The fit method returns a history object that contains information about the training process, such as the loss and accuracy of the model at each epoch.