Public WiFi does have it's security problems. If your worried about someone eavesdropping on you (and that's a very real possibility), there are several VPN solutions for Android.

I have used AVAST Antivirus for years (It's free and decent), and they make clients for both Windows and Android.

They also have a Secure VPN client just for Android. It's a subscription, and not free, but it works very well and would take the risk out of using public Wifi.