Still doing good in English, I hope.

Sentence---Yesterday during the tornado watch, we heard the wailing of the siren in the pathway.
A gerund always ends in -ing and functions as a noun. Ok during is not a gerund but wailing is a gerund. Am I right?

You are correct. :-)

Yes, you're correct! A gerund is a verb form that functions as a noun and always ends in -ing. In the sentence you provided, "wailing" is indeed an example of a gerund. It functions as a noun because it is the subject of the sentence.

To determine if a word is a gerund, you can follow these steps:

1. Identify the word that ends in -ing.
2. Consider the role it plays in the sentence. If it acts as a noun—such as the subject, object, or complement—then it is a gerund.

In the sentence "Yesterday during the tornado watch, we heard the wailing of the siren in the pathway," "wailing" is the subject of the verb "heard" and fulfills the role of a verb functioning as a noun.