The last time Camera FV-5 was updated was in November 2017. To say it is getting a bit long in the tooth is an understatement. That was only three months after the initial public release of Android 8.0. A lot of reviews for Camera FV-5 are negative and indicate that it causes a wide variety of phones to crash when certain features are accessed. It may be that your phone will not fully work with Camera FV-5.

In the "pro" mode, I could find the setting for ISO but not for aperture and the shutter speed.

The shutter speed (exposure time) is to the right of ISO. It is currently showing 1/17 seconds as the exposure time.

Very few smartphones allow aperture control because the vast majority of smartphone cameras do not have an adjustable aperture. The aperture in the lens is fixed. Most phone cameras that appear to allow "aperture control" simulate changing the aperture by using software to process the images from two different cameras facing the same way.

To the best of my knowledge, the only smartphones with cameras that actually have an adjustable aperture are the Samsung Galaxy S9, S9+, Note 9, and the currently available Galaxy S10 and S10+. They only have two - count 'em: two - aperture settings, f/1.5 and f/2.4. The recently announced Galaxy Note 10 and Note 10+ include a camera with three stage aperture offering f/1.5, f/1.8, and f/2.4.

What is "EV" and "AF"?

EV is exposure value. In this context, it actually means exposure compensation, which is basically a way of telling the camera to expose brighter or darker by a certain amount than what the camera thinks is the "correct" exposure. Most camera meters think everything should wind up to be about as bright as medium grey.

AF is autofocus. AF-C stands for "Continuous AF", which means the camera is constantly refocusing on whatever it is pointed at until the picture is taken. AF-S stands for "Single AF" in which the camera focuses on what it is pointed at and then locks in that focus distance until the picture is taken, even if the camera is repointed or the subject moves.