This is the 468th most frequent Turkish word.
okul
School.
Here, 'okul' refers to a physical building, the school.
Okul çok yakında, yürüyerek gidebilirim.
The school is very close; I can walk there.
In this sentence, 'okula' (the dative case of 'okul') indicates movement towards a school.
Her sabah okula zamanında varıyorum.
I arrive at school on time every morning.
Here, 'okul hayatı' ('school life') uses 'okul' in an abstract sense, referring to the experience related to schooling.