Questions & Answers about Вилка лежит на столе рядом с тарелкой.
Why is стол in the form столе here?
Because the preposition на can mean “on” in two senses: static location (where?) and direction (куда?). For static location you use the prepositional case. стол → столе means “on the table.”
Why is тарелка in the form тарелкой instead of тарелке?
Because the phrase рядом с (“next to, beside”) consists of the adverb рядом plus the preposition с, and с always takes the instrumental case. So тарелка (nominative) → тарелкой (instrumental) after с.
What does лежит mean, and why not стоит or сидит?
лежит is the 3rd-person singular present of лежать, “to lie (horizontally).” In Russian you choose the verb of position by orientation:
• лежать for a horizontal object
• стоять for a vertical (standing) object
• сидеть for seated beings
A fork lies flat, so you say вилка лежит.
What part of speech is рядом, and why can’t I just say рядом тарелкой?