Welcome to the forum!
The first question to ask you is whether you've updated your system. There was a major update on the 19th of July, and the latest install images are not yet up-to-date.
So, if you haven't updated your system yet, open up a terminal window and issue the following command...
sudo pacman-mirrors -f 5 && sudo pacman -Syyu
This will take a long time, because as I said, this was a major update, covering many packages. Just let it finish, and then install the package
ttf-dejavu, like so...
sudo pacman -S ttf-dejavu
Once that too has finished ─ it should only take a short time ─ you must reboot the system. However, because there has also been an additional update to GRUB ─ the boot loader ─ yesterday due to the Boot Hole vulnerability, and given that some people are experiencing boot problems after updating GRUB, we're going to take an extra step in preventing you from running into the same boot problem.
So, while you still have that terminal window open, issue the following two commands, and then you should be ready to go.
sudo grub-install --recheck --no-rs-codes
Now it should be safe to reboot.