Instrumentals with vocals?

[Bojo]

Newbie here, confused.

There are a number of listings such as "Hip-hop instrumentals" and pop/r&B-insturmentals.

Trying to keep this short…What do they want?

A beat with no vocals? But sometimes they speak a lot about vocals….and melody… Here for example, #Y130925HH, they speak about a "vocal hook". So should this hook be included? Probably. But how can I make a vocal hook just like that without knowing what the lyrics are? Should I use ohs and ahs? Should I just pick a generic phase "I love you" or something? I mean the artist probably has some kind of idea for the lyrics, love, crime, today´s weather or whatever.

Here´s another, # Y131007IN:
"This artist is great with melody, so don't be afraid to go outside the box musically."

But it's an instrumental? Do they want a melody (played on an keyboard for example) so they can but lyrics to it?

/Bojo, Sweden