OK, being before coffee didn't help, I thought you were asked to convert concentration to some strange unit, but it wasn't clear whether you are asked to convert 18 M or 5% m/v.
Yes it should be mol/L and that is what it’s asking
You have still not shown what you have tried.
5% m/v - what does it mean?
How much acetic acid in 1 L of 5% m/v solution?