What boosting means depends on which Fediverse platform you’re on. If you’re following Kbin content from Mastodon/Calckey/Pleroma, which are conceptually similar to Twitter, boosting appears in your feed in the way that a twitter retweet does.

If you’re following Kbin content directly on Kbin, then a boosted article will appear in your profile. I don’t know what Lemmy or other Fediverse applications do with them.