You don't want to pickle the predictions but rather the fit.

Change joblib.dump(nb_predict_train, "trained-model.pkl") to joblib.dump(nb_model, "trained-model.pkl")

Your question leaves a lot unexplained, but the error you're receiving probably came from the last line vectorized_text = features.transform("Heathcare is good").toarray().
The variable features is itself an array (it came from features = ... .toarray()).
I'm assuming you meant to replace it with
vectorized_text = tfidf.transform("Heathcare is good").toarray()?

The problem is that train_test_split(X, y, ...) returns numpy arrays and not pandas dataframes. Numpy arrays have no attribute named columns

If you want to see what features SelectFromModel kept, you need to substitute X_train (which is a numpy.array) with X which is a pandas.DataFrame.

selected_feat= X.columns[(sel.get_support())]

This will return a list of the columns kept by the feature selector.

If you wanted to see how many features were kept you can just run this:

sel.get_support().sum()  # by default this will count 'True' as 1 and 'False' as 0

This is more of a programming question than a data science question and is therefore better suited for stackoverflow. The vectorizer is trying to convert the string values to lowercase using the .lower() method. However, you are passing in a numpy array, which does not have this method. Instead of passing in a numpy array, you can simply use a pandas dataframe (which does have the .lower() method, see the documentation) by removing the .values attribute in dataset.iloc[:,:-1].values.

Passing sklearn's LinearRegression() as an instance solved this problem:

model = RegressionModel(lags=[-1, -2, -3], model=LinearRegression())

You are using the variable name image in your code, while you also import a module named image. This conflict results in trying to find img_to_array method in the variable rather than in the module.

Use a different name for you image variable, or directly import the img_to_array function:

from keras.preprocessing.image import img_to_array
[...]
x = img_to_array(img1)