If you mean a specific one, this object takes the oblique.
kmr.morph.present-object-case · Hint · Word form
In the present the object of a transitive verb is oblique: Ez pirtûkê dixwînim, "I read the book". Without the ending it reads as general, "I read books", which may be what you mean.
Examples
| Wrong | Right |
|---|---|
| Ez pirtûk dixwînim | Ez pirtûkê dixwînim |
| Tu jin dibînî | Tu jinê dibînî |