How to make a humanoid npc jump?

Setting the Jump to true in an Humanoid so everytime Jump() is called the NPC will jump.

function Jump()
local NPC= Workspace.NPC:FindFirstChild("Humanoid")
if NPC then
NPC.Jump=true
end
end

As you secondarily wanted to learn how to make the NPC jump constantly .You would use the while loop

function Jump()
local NPC= Workspace.NPC:FindFirstChild("Humanoid")
if NPC then
while wait (1) do
NPC.Jump=true
end
end

In the script above when the function Jump() is called the humanoid's jump property will constantly be set to true every time second since the property itself is set to false automatically every time it is set to true.