Questions & Answers about Её фартук висит на кухне рядом с прихваткой и полотенцем.
Фартук is in the nominative singular. It is the subject of the sentence: it is the thing that is hanging.
This is also the dictionary form of the noun:
- фартук = apron
So the basic structure is:
- Её фартук = her apron
- висит = is hanging
Because only фартук is the subject.
The sentence mentions:
- фартук = the apron
- прихваткой и полотенцем = with / next to the potholder and towel
But прихваткой and полотенцем are not extra subjects. They are part of the phrase рядом с... meaning next to...
So the verb agrees only with фартук, which is singular:
- фартук висит = the apron is hanging
If the apron and towel were both subjects, then you would use plural:
- Фартук и полотенце висят.