"Will you stay here?"
The preposition 在 (zài) can sometimes appear after the verb. This can be confusing for people learning Chinese, because in most constructions prepositions like 在 should come before the verb.
But with verbs that indicate position, movement or placement, 在 should come after. For example, 在 will almost always comes after 住，坐，etc.
In this case, 留 also indicates placement. Therefore we should place it after the word 在.