This is the 1335th most frequent Japanese word.
o
The Japanese word "o" (を) is a particle that marks the direct object of a verb.
In this sentence, 'o' is a particle marking 'book' (本, hon) as the direct object of the verb 'read' (読みます, yomimasu).
私は本を読みます。
I read a book.
Here, 'o' serves as a particle marking 'station' (駅, eki) as the point being passed during motion, a use related to the 'object marker' function.
駅を通りました。
I passed by the station.
In this example, 'o' is used to indicate the street (道, michi) as the location in relation to the motion activity 'walking' (歩く, aruku).