Where to find explanation what is entity for

I have bought Fibaro Walli roller shutter (z wave) and connected it to HA (I have outside blinders).

HA associated the device and added 10 entities. Calibration worked and position is correct reported to HA.

There are many entities under the device and I am not sure what is purpose of many entities.

There are two switches for control, I assume one of them would be for tilting if I had venetian blinders… maybe… or perhaps they represent top and bottom button?

Bottom line is I don’t know and I want to know. How can I understand each entity?

I have disabled some entities for now and can control it, but it bugs me.

Not sure what the basic sensor is for, but alarm type and level show up in various z-wave devices. Check here for some basic insight.

Generally, these are used to communicate status changes of one type or another, as an example with my own z-wave lock:
alarm type 22 - lock has been opened with a key instead of a code or remote signal
alarm type 27 - closed by the auto-lock function
alarm type 9 - lock jammed

I think it is done this way to allow for easily connecting to something like a Smartthings system and having that system be able to interpret statuses properly.

Check the attributes of the main entity for your roller, with my lock the status messages are passed through as clear text in the main entities attribute fields. If this is the case for you, you should be able to confirm what alarm level and type values correspond with each status.