On the top left of my iPad it says no service, what does that mean?

I

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on top left of iPad it says no service, what does that mean?

I play trivia crack but when I tap on app after a couple of seconds it goes back to home screen. And on top left of screen where it shows the fan like thing that shows you your lines of your wifi it says no service. Could this be my problem with trivia crack? I get online so what could be the problem?