Signs like this are in a hierarchy, with the main restriction always at the top, (the yellow sign). The top sign should be well familiar to you because it is used all over the place and always contains the 'No Waiting" (aka no parking), symbol, with the times when it is banned. In you case from 7.30 pm to 8.00 am.
Then below this, the times when parking is free, and then below that, a sign for when payment must be made.
What made you think parking was free all night when there is a sign that says it isn't ?