If you are extremely new to web development, and you are not interested in how a server works, XAMPP can help you to setup a PHP + MySQL + Apache server in half an hour.
XAMPP runs on Windows, Linux and Mac OS.
It is not recommended, but I have to put it here because it's really the easiest way. You can find more information about it on the official website above.
I'm afraid of someone can hardly realize that if he have insatlled XAMPP, none of the rest document is necessary.
If you didn't open the XAMPP website, or you are not deploying your first web server, the following will help you.
First, suppose you have chocolatey installed, it's not difficult at all.
choco install -y php mysql apache-httpd
Make sure you have a stable Internet connection and the packages will be installed after several minutes.
Most of Linux distributions have these packages in package manager. For example, in Ubuntu > 16.04
sudo apt-get install -y apache2 php
sudo apt-get install -y php7.0-fpm php7.0-mysql php7.0-common php7.0-mbstring php7.0-gd php7.0-json php7.0-cli php7.0-curl libapache2-mod-php7.0
sudo apt-get install -y mysql-server-5.7
Similar to Linux, will be completed later.