Safari

I understand you want to close an open Safari window. File > Close Window should work, as does its keyboard equivalent ⇧ ⌘ W. Similarly, ⌘ W closes an open tab. If that is not working something is obviously not working as intended.

Please determine if the same problems occur in "Safe Mode": How to use safe mode on your Mac - Apple Support

Which model MacBook Pro do you have?

Identify your MacBook Pro model - Apple Support

Please describe what you are trying to do.

Where is the power button?

Which model Mac do you have?

The power button is at the top row of keys, far right side. On newer portable Macs the Power key is also the Finger Print ID key.

The power button on your model MBP is the key at the upper right corner of its keyboard. It is also used for Touch ID.

Press and hold to force the Mac to shut down.