So i went to the beach and my phone is linked to my email. My i was reading new reports via google news reports, via my email/ phone and it died. When i got home and plugged my phone it, it wanted me to re-enter my password which wouldnt wk. I tried to log in at home and it said something like email compromised and it made me reenter my password and then change it. I can still access my account and stuff. What exactly was compromised and what can i do to keep it from happening again??

and what is a strong password to avoid being hacked? give an example please