Deleted startup disk and disk, what do I do? Haven’t used Mac in a while, gave to my mom, got it back like this, is there any way to save it?

You can reinstall the operating system using the Internet Recovery Mode. On startup, press:

• Shift + Option + Command + R keys install the OS that originally came with the Mac.
• Option + Command + R keys to install the latest OS that is compatible with your Mac.
• You need to have the Mac connected to the internet. Do not use Wi-Fi as it is too slow and the downloaded files are likely to get corrupted. Use the wired Ethernet connection.