A lock symbol

Hello everyone.

want to ask anyone knows what the lock symbol with a ring around has appeared on my iPhone for. It is on the upper right corner next to the arrow symbol and battery percentage symbols.

I think it appeared when I recently went from home in CT to PA. Why is it there and how do I get rid of it ? Tia to everyone who can help me out. I have a iPhone 8+ And here is a screen shot of the symbol in question :

Rita C