In one sentence, describe what the following article is about:

Attach your SD card adapter to one of your Mac's USB or USB-C ports, then plug the SD card itself into the adapter. If you have an older Mac, your Mac may have an SD card slot on its right side. If so, you can plug the SD card label side-up and gold connectors-first into the slot. In some cases, having one read-only file can cause the whole SD card to lock down until the file is switched to "Read and Write" mode. You can check a file's status by clicking it, clicking File, clicking Get Info, and looking at the "Sharing & Permissions" heading. If your file is read-only, change it to "Read and Write" status to see if that removes your SD card's digital write protection. Click the magnifying glass-shaped icon in the top-right corner of the screen. A search bar will appear in the middle of the screen. Type disk utility into the search bar, then double-click Disk Utility in the search results. Click your SD card's name in the upper-left side of the Disk Utility window. It's a tab near the top of the Disk Utility window. Doing so will prompt First Aid to begin running on your SD card. If prompted, follow any on-screen instructions while First Aid runs. If your SD card is locked down due to an error, the error will be fixed by First Aid.

Summary:
Plug your SD card into your Mac. Look for a read-only file. Open Spotlight . Open Disk Utility. Select your SD card. Click First Aid. Allow First Aid to scan the SD card.