what do the icons on top of the screen on my ipod touch mean

The circled padlock means the screen rotation is lock in portrait mode

From page 27 od iOS 4.1 Touch Users Guide:

Lock the iPod touch screen in portrait orientation (iPod touch 3rd generation or
later): Double-click the Home button, flick the bottom of the screen from left-to-right,
then tap (icon black square round arrow)
The portrait orientation lock icon (circled padlock) appears in the status bar when the screen
orientation is locked.

I do not know what the other one means. Try looking at the users guide.

All the icons are covered in the manual.

Have a look:

http://manuals.info.apple.com/enUS/iPod_touch_iOS4.1_UserGuide.pdf

sseligson wrote:
... Yesterday I had an arrow head point diagonal to the right. What do these mean?

The Play button? (Music playing!)

Phil