Yes, NLP is on-topic here.
We have more than a dozen questions already under the nlp tag; almost all of them have net positive scores, and about half of them are answered.
The example question has already received an accepted and upvoted answer, though, so migration is not really called for in this case. You can read What is migration and how does it work? for a thorough discussion but the relevant bit is quoted below:
Avoid migrating answered questions. The point of migration is to send the question to an on-topic place when it can get answered. If the OP already has an answer, then we've already defeated the purpose of migration and the destination site won't have anything to do with the question. Avoid migrating these questions unless they are of extremely good quality and risk deletion on the current site.
Don't migrate for the sake of migration. We only migrate questions because they are off-topic on this site. It is perfectly possible for a question to be on-topic on multiple sites, but that is not a reason to migrate it elsewhere. The OP asked their question here, so if it's on-topic here, then it should stay here.
Stack Overflow also has a tag for NLP and while they might prefer to stick with the more technical implementation questions, that distinction isn't always clear, so it seems reasonable to leave this question where it was asked. A nice compromise might be to leave a comment recommending our site for the asker and future visitors to the page.