The full sentence was 人気のある情報を見る, found on a button. Why would のある instead of for instance な
人気 works both as a noun ("popularity") and as a no-/na-adjective ("popular"). The following sentences mean the same thing:
"Pokémon is popular with children."
English speakers don't usually say "there is popularity", but Japanese speakers do say 人気がある for whatever reason. Both sentences are very common and I don't even know which is more common.
Naturally, you can construct relative clauses from them. The following noun phrases mean the same thing:
"a Pokémon which is popular with children"