What's on television?
What's on the television?
I have read in my book that we often do not use 'the' with television.
The first sentence is about the show currently being shown. So,in my opinion,the second sentence is about what is kept on the television box.
Please correct if I am wrong.
You are right. Remember that television can mean (at least) 2 things: a piece of electrical equipment with a screen, used for watching programs, and the system of broadcasting pictures and sounds by electronic signals.
If we mean the first, then we may need to use the/a/no article, depending on the situation:
They sell many different televisions.
What is on the television? - Flowers are. (see the picture below)
If we mean the second, we normally don't use the (we never use a because television is uncountable now):
What's on TV? - Nothing special.
