If you have a server, you probably want to install PHP.
A while ago I thought PHP is really primitive (I only used Java/JSP) but WordPress has changed that forever.
Install PHP and PHP MySQL library (you will probably need it)
sudo apt install php libapache2-mod-php php-mysql
Install additional PHP libraries (whatever you need)
sudo apt install php-pear php-curl php-dev php-gd php-mbstring php-zip php-xml
(you may add other extensions now, or install what you need later)