Termux – Termux is an Android terminal emulator and Linux environment app that works directly with no rooting or setup required. A minimal base system is installed automatically – additional packages are available using the APT package manager.

termux-setup-storage
cd – change directory
ls – list out
cd .. – get back from that directory
pwd – present working directory
mkdir (directory name) – make new directory
rmdir (directory name) – remove directory
clear – clear the screen
apt update – update the package
apt upgrade – upgrade the pakage
apt list – list out the packages
cal – shows calculator
time – shows  time
ifconfig – show your ip address
free – display memory and swap usage
whoami – show your login name

* Necessary Packages –
Pkg install python
Pkg install python2
Pkg install php
Pkg install curl
Pkg install figlet
Pkg install wget
Pkg install pip
Pkg install php
Pkg install git
Pkg install rust
Pkg install make
Pkg install perl
Pkg install dnsutils
Pkg install redit
Pkg install xtreme
Pkg install bash
Pkg install lolcat
Pkg install clang
Pkg install tor
Pkg install mdk3
Pkg install hashcat
Pkg install beef-xss
Pkg install sslstrip
Pkg install bully
Pkg install iptables
Pkg install hostapd
Pkg install dsniff
Pkg install dhcp
Pkg install aircrack-ng

I hope you clearly understood the basis of termux.