I just wanted to install Skype but it says that this app can access to all my personal files and system resources. What does this mean? Does this means that somehow Skype can copy, delete or open my personal files? or change my computer setup like installing files, etc? Is it safe to install Skype app? Thanks.
Any Deb application can open/read/copy/delete any of your personal files already.
Any Snap application can open/read/copy/delete all non-hidden (non-.dotfile) personal files already. This is more limited access than Deb applications.
Any Deb application can change your system already (install/remove scripts run as root). This is why it's very important to install only from trusted sources - a malicious package can do tremendous damage.
A Snap application is confined by AppArmor rules. It cannot make changes to your system. It cannot even read many system files.
Skype is distributed today as either Deb, Snap, etc.