Hi angelawesome01,
What year was your MacBook Pro made in? Click the Apple logo in the top left corner, then choose About This Mac. If it doesn't show there, provide your serial number to Apple's Check Coverage website: Check Your Service and Support Coverage - Apple Support
Once we know when your MacBook Pro was made, we can figure out what version of macOS it supports.
When you mention that you're unable to download apps, is this just for apps from the App Store, apps from other places, or both? Do they refuse to install because your version of macOS is too old?
About the freezing, please download EtreCheck and generate a report. Paste the full text report here. (When composing, click the document icon in the toolbar, then paste the text report there.)