Nothing is wrong with this script, yet this question lacks details, we really can't help you with the amount of information you give us, like, what IS exactly "not working"?
The only thing that seems ODD is that, the supposed mesh that is falling on the player, which is called "a", is located in "game.ReplicatedStorage", If you want your part to show on the map it must be located in the Workspace, so maybe try this?
local hi = script.Parent
hi.ClickDetector.MouseClick:Connect(function()
local mesh = game.ReplicatedStorage.a
mesh.Parent = game.Workspace
mesh.Anchored = false
mesh.Transparency = 0
end)
If that isn't the problem tho, we will need more information to actually be able to help you.