Hi, and welcome!
Please see the FAQ: What's a reproducible example (`reprex`) and how do I do one? Using a reprex, complete with representative data will attract quicker and more answers.
This may be a particularly hard one to reproduce, however, without guessing that the gtrends is in the gtrends$ package. (Lucky guess on my part.)
The only way to answer without a reprex (and getting one's own API key if needed) is to look at the help(gtrends) page.
The answer is right in the Arguments section
geo character vector denoting geographic regions for the query, default to “all” for global queries. Multiple regions are possible using gtrends("NHL", c("CA", "US")).