I don't understand the question or JOINS

It doesn't specify if it's left join with the Genres table. Since it states use Media_Genres table to join two tables, so I think we should understand that first two tables are joined - Media and Media_Genres, and now we will join the third, Genres, table but only if Media_Genres table has similar column with Genres. We have to understand this way, like it's being optional data from Genre if certain conditions meet on first and second tables. It's left outer join of Genres table; some of the data from Genres table will not be listed in a new created table. Also, WHERE clause should be included, and it should be the query from the main table, Media table.

select * from Media join Media_Genres on Media.media_id = Media_Genres.media_id left outer join Genres on Media_Genres.genre_id = Genres.genre_id where Media.media_id=3;