Macbook Air restarts for update, but don't do anything

Hi,

When I try to update my Macbook Air (it shows 1 update available ), it doesn't do anything but restart when I click restart.

This is what I get:

In the software update screen > update available > Install update

"To install the updates, you must restart your computer. To finish the installation and restart your computer, click restart." > Restart

Then my MacBook restarts, but doesn't update anything.

It just restarts like it normally would when you click restart.

I tried a couple of times, but the update is still available in the software update.

Can anyone tell me what I should do?

Thanks in advance!

Regards,