Have text box appear once a character has been hovered

The easiest way to do this is by adding a Hover state to the character. 

Select the Character and go to the "States" Tab. Select EDIT STATES and add a new state HOVER from the dropdown.

Select DONE EDITING STATES.

Now select the text box you want to appear when you hover over the character and cut it (CTRL+X)

Now go back to your character and select the EDIT STATES button again and then select your HOVER State. Now Paste the text box you copied into that state. (Ctrl+V)

You can copy the text box, then create the Hover state, and paste the box without having to leave and re-enter the editing mode.

Or, did you want the text box to be  a Text Entry box?, or did you want it to stay visible even when not hovering?

Actually, I am able to create the hover the box. But once the learner has seen the text when they hover I would like to have another text box somewhere on the slide to appear. 
i have tried with change state of the text box to hidden when timelines starts then change state to normal when character is hover but It doesn’t work... any suggestion? 

Perhaps on the trigger to change the state of the second box you need to deselect  Restore when hover off.

Here is a sample with two options. One of them may work for you.