Terminal is the macOS default comand line program. It is part of the operating system so every mac should have Terminal.
How to Start Terminal
1. Open Launchpad
2. Open the Other app folder and click Terminal
Terminal will open in it's default location. Meaning it you will be executing comands in the context of the default location.
How to start terminal in a specific location
Usually you will want to start terminal in a specific location, which means that you will be executing comands in the conext of that location. If you need to run a program for example then you would normally use terminal in the location that the program is saved in to start it.
There are probably many ways to do this but here are a couple:
Right click on the folder where you want to start Terminal and select New Terminal at Folder
The screenshot below shows right clicking on the folder in the path bar (if you don't see the path bar in Finder go to View > Show Path Bar)
The screenshot below shows right clicking on the folder in finder
How to Copy a path
1. Use a Short cut key Add a cursor to the folder: ⌘command+option+c
2. Or you can Click the path then copy from the right-click menu.
Navigate to a directory using the "cd" command
Execute the comand
Where [path] is the path of the location you want to change to
Use the command history
In Terminal you can easily recall comands that you have used before in this Terminal session by clicking the arrow buttons. To start with you use the Up arrow ↑ on the keyboard to go to old comands. You can also use the down arrow to get to newer comands.