Translation:The library has many books about art.
And to be fair Spanish, Portuguese, French, German, Italian, Russian all have something that sounds like biblioteko. Although the "biblio" prefix might make less sense in Esperanto since it means Bible, and "libro" might make more sense since it means book, there was no contest, really.
A really relevant Duolingo forum discussion about the etymologies of library and bookstore For your convenience And Wordhippo but it doesn't really sort by type of language beyond continent
The suffix -aro seems to combine with a noun's root to form a new noun that represents a collection of original noun. As seen here, an example of this is ŝtupo (a step) - ŝtuparo (a staircase).
If we follow this logic then libraro would probably mean something such as "a collection of books, that are considered as one entity". This contrasts to biblioteko which refers to "a building or room housing a book collection, library".