Windows 11 comes with the Taskbar centred on your screen, which is a change from all previous Windows versions, where it was always aligned to the left.
If you prefer your Taskbar to be aligned to the left, you can change the position.
Right-click on a blank spot on the Taskbar and select Taskbar settings (as shown below):
Or alternatively Click on the Windows button, go to Settings and choose Personalisation > Taskbar
Then select Taskbar behaviours and change the alignment:
With the upgrade to Windows 11 it will default to Centre, but can be simply changed back to Left which will match what you will have been used to with Windows 10.
See the Windows 11 Rollout site for more tips on Taskbar customisation and other useful Win11 information.