This is the 4251st most frequent Russian word.
юлии
"Юлии" is the plural form of the name "Юлия" (Julia), referring to multiple individuals named Julia.
In this sentence, "Юлии" is in the dative case, indicating the person experiencing the feeling - Julia.
Юлии было неприятно слышать об этом.
Julia felt uncomfortable hearing about it.
Here, "Юлии" is in the dative case to express possession in combination with the verb "принадлежать" (to belong).
Эта книга принадлежит Юлии.
This book belongs to Julia.
In this context, "Юлии" is again in the dative case, indicating the indirect object of the action of giving.