What does "Vertical search " is meant for ?

your question makes no sense grammatically. Also, why don’t you add a description.

“Vertical” search is search through just one site instead of many sites. Like the search bar on Fluther. That is a vertical search, because it just searches pages on Fluther, not the whole internet.

Vertical and horizontal, when used to describe technology, generally have the same connotation. Horizontal is “wide/parallel”, and vertical is “deep/monolithic”.