is there a way where i can see a features information by hovering the mouse over it without clicking?
Yes there is
Look at this great example made by Larry_Stout
ArcGIS Web Application
It was made by WAB Dev.
On which layer is it exactly working?
i tried to hover the mouse on top of many layers but i couldnt see any popup or information
I think the taxlots layer
I see it is working but how did he do it? Can it be done in Web App Builder? Or do you have to be a developer?
It is not an OTB feature so Larry as Developer programmed that ability.
I figured that. I got yelled at after upgrading our old Silverlight map and moving to the HTML5 web app. Sure more devices can use it but that hover over was nice for my office users. Can’t make everyone happy right! ☺
Right you can't make everyone happy and when your silverlight app just stops working one day they will like that even less.
Oh, that is long gone already!!! ☺
Great application! Are you aware if the source code is available online?