That’s the usually-going-to-be-storage-constrained 256 GB Physical Solid State Disk using GUID partitioning (GPT), containing an APFS container (“disk3”), and that APFS container with macOS itself including partitions within that for the read-only secure file system (“Macintosh HD”) and for user data (variously “Macintosh HD - Data” or “Data”).
Pretty typical, in fewer words.
For what technical details of APFS are available from Apple: Introduction
About apps and file systems more generally: About Files and Directories
An issue for many folks with a Mac with 256 GB is available storage, and there’s not much that can be done about that within Disk Utility, absent some user-added partition. None of those are present or visible here.
If you want to see the list of disks (past the disk1 blue and disk2 orange containers shown just below that big red bar, and that big red bar is effectively disk3), launch Terminal app and use the following command-line commands, as a starting point:
diskutil list
diskutil info {whatever}
These two particular diskutil command-line commands are harmless, though other diskutil commands..l aren’r so harmless.