What does the execute permission mean for a directory? What is stored in /etc, /var, /dev directories?

Execute permission for a directory in Unix-like systems means the ability to "enter" this directory, i.e., access its contents by name. Without execute permission, it is impossible to access files inside the directory, even if read permissions are granted.

What is stored in these directories:

• /etc — configuration files of the system and applications. Here are the settings that affect the operation of the system.
• /var — variable data that changes during system operation: logs, mail, databases, cache.
• /dev — special device files that represent hardware devices and virtual interfaces.

Thus, execute permissions for directories are important for navigation and access to files inside them.