"Terbaik untukmu" means "best for you," so the post seems to be suggesting a free download of what they consider to be some of the best Western semi-movies or series for the reader.
The phrase "film semi barat" translates to "Western semi-movie" or "Western-style semi-film" in English. "Semi" can imply something that's not entirely full-length or feature film but could be a short film, a clip, or possibly a TV series.
If you're looking for "semi" content, you might consider looking into short films or series episodes that are legally available on platforms like YouTube, Vimeo, or specific genre-focused streaming services.