For MacOS and Linux operating systems, an SSH client is installed by default. For Windows 10 this is an optional feature that you can enable. There are also other 3rd party tools out there that enables SSH for your OS. For example PuTTY (Windows, Free) or Prompt (MacOS, Payed).
The Raspberry Pi Foundation has written documentation on how to setup SSH
If you do not know how to SSH to a Raspberry Pi, please read their documentation on how to use SSH.