After completing installation of Termux, then run these all commands. its specially for begginers:
apt update && apt upgrade
pkg update -y && pkg upgrade -y
pkg install python -y
pkg install python2 -y
pkg install fish -y
pkg install ruby -y
pkg install git -y
pkg install php -y
pkg install perl -y
pkg install nmap -y
pkg install bash -y
pkg install clang -y
pkg install nano -y
pkg install w3m -y
pkg install hydra -y
pkg install figlet -y
pkg install cowsay -y
pkg install curl -y
pkg install tar -y
pkg install zip -y
pkg install unzip -y
pkg install tor -y
pkg install wget -y
pkg install wcalc -y
pkg install bmon -y
pkg install golang -y
pkg install openssl -y
pkg install cmatrix -y
pkg install openssh -y
pkg install wireshark -y
pkg install toilet
pkg install sl
pkg install vim
pkg install tch
pkg install zsh
pkg install fortune
pkg install zsh