What you are seing in Disk Utility is how macOS handles drives in macOS Big Sur and later. There is really no need to expand the volume to see the seperate partitions.
The Volume Macintosh HD has 2 seperate APFS volumes that act as 1. The Macintosh HD houses the system Software and Macintosh HD - Data has all of your data, apps, etc. As far as your concerned you will only see Macintosh HD, and the system will act as if you only have a single partition,
As far as Macintosh HD 2 - Data - Data volumes. Does this show up on your desktop? are there any files on it?
If there are no files on it, you should be safe to right click on the top volume and delete the APFS volume.
Of course as always before doing anything, you should backup your computer 1st.
