やっと- finally
映画館 - cinema
ポップコーン - popcorn
食べられました - was able to eat
やっと映画館のポップコーンを食べられました - I finally got to eat popcorn from the cinema もしくは I was finally able to eat popcorn from the cinemaになると思います。
I love the popcorn from the cinema, so I was so happy when I was finally able to eat it.
I love cinema popcorn, so I was so happy when I finally got to eat it.
イギリス 
