Why is this on my iPhone 4s screen?

This picture of a charger cord pointing to an iTunes symbol popped up randomly on my iPhone 4s and now I can't use it. It seems as if it may be asking me to connect my phone to iTunes. BUT WHY!

I don't really know but I would definitely plug it into itunes just in case its having some technical issue, my phones done that before and completely shat itself so I say follow its instructions friend

As to why, not sure, didn't really provide much in terms of details, but at least should do what it says.