This is the 11929th most frequent Turkish word.
gideceğini
"That he/she/it will go."
In this sentence, 'gideceğini' is used to indicate a reported action in the future (that she will go somewhere).
Yarın tatile gideceğini söyledi.
She said she would go on a vacation tomorrow.
Here, 'gideceğini' refers to the second person's future action that has been mentioned as knowledge being shared.
Senin bu akşam bizimle gelmeyeceğini, ama yarın pikniğe gideceğini biliyoruz.
We know that you won't join us tonight, but that you will go on a picnic tomorrow.
Here, 'gideceğini' depicts a hypothetical or considered action in the future based on a condition.