Verbal irony is irony that is either spoken by characters or contained within the words of a story. Often, a writer will describe one thing but the reader gets a very different idea when reading it. A speaker may say one thing but mean another.
This story begins on a fine spring morning, but almost immediately we have a sense that something is amiss. This is due to the foreshadowing the author uses. The children are playing innocently in the street, but what are they doing? Collecting rocks. This does not seem odd at first, but we keep reading and see that they are piling the rocks up and guarding them. This intimates that they are going to use them later, and that is scary, since they are rocks. Why would innocent little kids be piling up and guarding rocks? Irony.
There is an example of verbal irony in the following:
Old Man Warner snorted. "Pack of crazy fools," he said. "Listening to the young folks, nothing's good enough for them. Next thing you know, they'll be wanting to go back to living in caves, nobody work any more, live hat way for a while. Used to be a saying about 'Lottery in June, corn be heavy soon.' First thing you know, we'd all be eating stewed chickweed and acorns. There's always been a lottery," he added petulantly. "Bad enough to see young Joe Summers up there joking with everybody."
The irony is that Old Man Warner says giving up the lottery would be a step backwards, like going back and living in caves like the cavemen, but what they are doing with the lottery, stoning each other to death, is acting like a cave man - it's primitive and uncivilized.
Lots more, but you get the idea. Read about the story here on enotes.
Just a caution concerning your question about verbal irony in Jackson's "The Lottery."
While some verbal irony exists in the "The Lottery, " most of the irony present in the work is not verbal. The quote from Old Man Warner cited above is a good example of verbal irony, for instance, but most of the irony takes another form.
I would suggest, for example, that the piling of the rocks does not suggest something is amiss. Foreshadowing gives the ending of a story legitimacy, but it does not provide hints. The point of the story is that the reader doesn't know anything is amiss. If the reader knows, then there is no surprise, and, thus, little or no horror. The horror comes from the surprise. We are not supposed to know something is up.
The detached, objective, limited point of view ensures that the reader doesn't know what the result of the lottery is until very near the end of the story. The story is carefully crafted to reveal only what appears natural, to only reveal the normal side of what's going on. Again, that's the point. Any verbal irony that occurs would need to be ancillary, not intentional.