The tag means the file was transcoded from a Blu-ray source. Subtitles marked for "BluRay" or "BRRip" will almost always work perfectly with your file because they share the same frame rate (usually 23.976 fps). Avoid subtitles marked "DVD" or "WEB-DL," as they might drift out of sync over time.
Since different regions have different language needs, these repositories are the most reliable for Ghibli films: subtitle When.Marnie.Was.There.2014.1080p.BRRip...
: Generally the go-to for specific scene releases like "BRRip." Look for the entry that matches your file name exactly. The tag means the file was transcoded from a Blu-ray source