MacOS partition concerns

Everything is normal.

The top entry is the drive itself.

The second is the APFS Container (like a partition in other file systems).

The third (volume group) is just a virtual grouping of the volumes within the container. Volumes are like a partition of a partition, but the storage of all volumes in a container is share amongst them.

The grayed out Macintosh HD is the System volume (the OS).

Macintosh HD snapshot is the sealed snapshot of the System Volume. The snapshot is mounted read only so it cannot be modified.

Macintosh HD - Data is the Data Volume and is where all of your data is stored.

There are several other volumes that used to be folders in previous version of macOS. They include VM (virtual memory), Recovery, Update, PreBoot. All are used to support the OS.

Don't delete anything that is shown in your screenshot as that is al required by macOS now.

macOS 10.15 Catalina was the first OS to begin using multiple APFS volumes within a single Container. Later versions of macOS have taken this a bit further and have modified the layout slightly as well.

APFS snapshots are basically meant to create a frozen read-only image of the file system at that point in time....usually for the purpose of backing up the data.

The "update" APFS volume is where new OS updates are now pre-staged before they are applied to the system.

The drive layout for Apple Silicon Macs has become even more complicated with even more hidden Containers holding critical software for the normal operation of the Apple Silicon Mac including support for 1TR (or One True Recovery).

The basic rule is if you did not create something, then do not delete it. In fact the only areas you have any control over are located within your own home user folder...even then you really only control the contents of the Desktop, Documents, and Downloads folders. Any other folder is partially controlled by macOS (like Music/iTunes, Photos) so take care making modifications elsewhere even in your own home user folder.

What you see in your Disk Utility screenshot is normal for Monterey & Ventura.

The Container is the partition that contains your macOS system, all your apps and all your data.

The Macintosh HD Snapshot is the signed & sealed volume (the "SSV") that your Mac actually boots from. The SSV didn't exist in Catalina, but does in Monterey & Ventura. The macOS installer created the SSV when you upgraded/installed Monterey or Ventura.

DO NOT DELETE any of what you see in your screenshot. If you do you will trash your system.

I’m not sure I can really explain it very well. I’m sure this will do a better job than I: https://eclecticlight.co/2021/07/31/explainer-snapshots/