Yes, you're right. The Yocto image doesn't include all the packages that you would normally find in a Linux OS for PC like Ubuntu. That's because they are different distros and Yocto is oriented for embedded applications which is not the same as the regular PC distros. Anyhow, the general principles are the same. You can navigate through the directories, create and edit files, create directories, check processes and other common tasks in the same way.
It's great that you are learning about Linux systems. I invite you to keep doing it, but keep in mind that you will find some differences when using the Yocto image for Galileo, for example the package management used by Yocto is opkg instead of the well-known apt-get.