why or how should i use these statements/strings?

Hi, Lordmunga! So I will give you some examples in common situations.

If statements:

So, let's say you have prepared a shop and some leader stats. You can put this script inside the button.

local Button = script.Parent --The button

Button.MouseButton1Click:Connect(function (Player) --Gets the player who clicked the button
if Player.leaderstats.Money == 10 then
print("Successfully purchased!") --If the player's money is enough to buy the item, a message in the console will print "Successfully purchased!"
end
end)

Elseif:

So, what if the money is not enough? This is where elseif and else come in.

local Button = script.Parent --The button

Button.MouseButton1Click:Connect(function (Player) --Gets the player who clicked the button
if Player.leaderstats.Money == 10 then
print("Successfully purchased!") --If the player's money is enough to buy the item, a message in the console will print "Successfully purchased!"
elseif -- We could actually just use else but we are using elseif just to double-check.
Player.leaderstats.Money < 10 then
print("Insufficient funds") -- If the player doesn't have enough money, a message will be printed in the console.
end
end)

While loops:

Let's say you want to spawn a part every second in the same place. You could use while loops.

while true do
local Part = Instance.new("Part", workspace)
Part.BrickColor = BrickColor.new("Bright blue")
end

Thanks for reading until the end.

If I helped don't forget to accept the answer!