This is the 318th most frequent Turkish word.
gösteren
"Gösteren" means "showing" or "displaying" in English.
In this sentence, 'gösteren' acts as a participle qualifying 'bir hikâye' (a story), making it 'a story that shows'.
Bu film, fedakârlığın önemini gösteren bir hikâye içeriyor.
This movie contains a story highlighting the importance of sacrifice.
Here, 'gösteren' is used to describe the 'ışık' (light) that indicates the way, functioning as an adjective.
Gösteren ışık sayesinde yolumuzu bulduk.
We found our way thanks to the guiding light.
In this sentence, 'gösteren' qualifies 'niteliğe' (quality), describing its function of showing or proving.