Breakdown of На столе лежали заколка, серёжки и тонкий браслет, которые она собиралась надеть вечером.
Questions & Answers about На столе лежали заколка, серёжки и тонкий браслет, которые она собиралась надеть вечером.
Because на столе means on the table in the sense of location.
After на, Russian usually uses:
- Prepositional case for location: на столе = on the table
- Accusative case for movement toward a place: на стол = onto the table
So:
- На столе лежали... = the items were already there
- Она положила заколку на стол = she put the hair clip onto the table
Because the real subject is the whole list:
заколка, серёжки и тонкий браслет
Together, these make a plural compound subject, so the verb is plural: лежали.
Even though the first noun is singular, the sentence is talking about several items lying on the table.