Some say that u can reinstall the mac os catalina. im still confused.
There are two volumes, "Macintosh HD" and "Macintosh HD - Data"
Macintosh HD is the system files and Macintosh HD - Data is your data.
If you select Macintosh HD in Disk Utility, it will show how much storage that volume takes, and how much storage the other volumes take up.
If you select Macintosh HD - Data, you will see how much space is taken up by your data, and how much storage space the other volumes take up.
Your data, Macintosh HD - Data, is the majority of "other volumes in container." It isn't some fluke or mistake. It is your stuff.
If you need to clear up space on your drive, then you need to figure out what files you have stored on that drive that you can either delete or move to another external drive. That is how you free up "other volumes in container."