I saw the Disk Utility, but the ERASE Botton doesn't work

You didn't mention WHY you need to erase all the contents of your MacBook Air. If you're trading it in or preparing it for sale, you'll want to follow the procedure in this Apple Support article: What to do before you sell, give away, trade in, or recycle your Mac - Apple Support

miaohaha wrote:

I need to erase all the contents of MacBook Air 13.

Follow these instructions:

Use Disk Utility to erase an Intel-based Mac - Apple Support

Use Disk Utility to erase a Mac with Apple silicon - Apple Support

If you are booted up normally, and try to erase the current startup disk, I don't think that Disk Utility will let you do that. You need to be booted up from another startup disk or from Recovery mode.