How do I fix this problem with a part being touched?

The reason your debounce isn't working is because you're using it incorrectly, firstly the parts where you change the debounce should be on the outer skirts of the function, you are also redefining the debounce locally inside the function First let's remove unnecessary if statements.

local brick = script.Parent
local buttonPressed = false

function onTouched(hit)
	if buttonPressed == false then
		buttonPressed = true
		if hit.Parent:FindFirstChild("Humanoid")~=nil and game.Players:GetPlayerFromCharacter(hit.Parent)~=nil then
			local player=game.Players:GetPlayerFromCharacter(hit.Parent)
			if player.Character then
				local stat = player:FindFirstChild("leaderstats")
				if stat then
					player.leaderstats.Coins.Value = player.leaderstats.Coins.Value + 1
					player.leaderstats.Wins.Value = player.leaderstats.Wins.Value + 1
					hit.Parent.HumanoidRootPart.CFrame = CFrame.new(-40, 1.5, 64)
					wait(10)    
				end
			end
		end
		buttonPressed = false
	end
end
brick.Touched:connect(onTouched)

Now the debounce should be working properly

Im going to combine your function and where you call it together now

local brick = script.Parent
local buttonPressed = false

brick.Touched:connect(function(hit)
	if buttonPressed == false then
		buttonPressed = true
		if hit.Parent:FindFirstChild("Humanoid")~=nil and game.Players:GetPlayerFromCharacter(hit.Parent)~=nil then
			local player=game.Players:GetPlayerFromCharacter(hit.Parent)
			if player.Character then
				local stat = player:FindFirstChild("leaderstats")
				if stat then
					player.leaderstats.Coins.Value = player.leaderstats.Coins.Value + 1
					player.leaderstats.Wins.Value = player.leaderstats.Wins.Value + 1
					hit.Parent.HumanoidRootPart.CFrame = CFrame.new(-40, 1.5, 64)
					wait(10)    
				end
			end
		end
		buttonPressed = false
	end
end)