(Easy?) How would i pick a random variables ?

local rng = Random.new()

local Map1 = script.Parent.Map1
local Map2 = script.Parent.Map2

local currentMap = rng:NextNumber() < 0.5 and Map1 or Map2

currentMap will now be a randomly chosen map from the two options.

Edit:

If you wanted to expand it to have more than two maps, you could do this:

local rng = Random.new()

local maps = {}
maps[#maps+1] = script.Parent.Map1
maps[#maps+1] = script.Parent.Map2
maps[#maps+1] = script.Parent.Map3
-- ..etc

local currentMap = maps[rng:NextInteger(1, #maps)]

Second Edit:

To change one of Map1 or Map2 to true you can do this:

local rng = Random.new()

local Map1 = script.Parent.Map1
local Map2 = script.Parent.Map2

-- In this case, either map will have a 50% chance of being set to true. You can also set the opposite value to false below if needed.
if rng:NextNumber() < 0.5 then
	Map1.Value = true
else
	Map2.Value = true
end