What H symbol mean at the top of my Samsung Galaxy Ace
It means your phone is receiving an HSDPA signal. HSDPA stands for High Speed Data Packet Access, and it means your phone is ready to connect to the internet at a speed that is faster than 3g. It isn't necessarily connected to the internet, as you would usually have arrows up and down showing that data was moving from the phone to the internet and back. If it is just the H symbol, then it usually isn't actually connected to the internet.