Find the total number of rentals for each genre
I've reduced a bit your table schema:

create table movie 
(
    id int primary key, 
    title varchar(20)
);

create table genre
(
    id int primary key, 
    name varchar(20)
);

create table movie_genre
(
    movie_id int, 
    genre_id int,
    primary key (movie_id, genre_id),
    foreign key (movie_id) references movie (id),
    foreign key (genre_id) references genre (id)
);

create table rental 
(
    id int primary key, 
    movie_id int
);


And then insert some values:

insert into movie values 
(1, 'movie 1'), (2, 'movie 2'), (3, 'movie 3'), (4, 'movie 4');

insert into genre values 
(1, 'genre 1'), (2, 'genre 2'), (3, 'genre 3'), (4, 'genre 4');

insert into movie_genre values
(1, 2), (1, 3),
(2, 1), (2, 2), (2, 4),
(3, 1), (3, 2), (3, 3), (3, 4),
(4, 2);

insert into rental values
(1, 1), (2, 2), (3, 1), (4, 3), (5, 1), (6, 3), (7, 4);


Now joining all tables and grouping by genre.name you can get the count of each genre:

select   g.name, count(*) rentals
from     rental r
join     movie  m
on       r.movie_id = m.id
join     movie_genre mg
on       mg.movie_id = m.id
join     genre g
on       mg.genre_id = g.id
group by g.name;




name    | rentals
:------ | ------:
genre 1 |       3
genre 2 |       7
genre 3 |       5
genre 4 |       3



dbfiddle here