Veronique
what a beautiful name and how good are you to be looking out for your FIL.
Welcome to this forum, we are generally speaking a useful friendly bunch of people to chat with.
First things first, it is early days as you say and waiting for those test reults, finding out what lies ahead is a really deeply disturbing time for most men. No wonder you FIL is all at sea. Once he has more information and has had time to comprehend what it all means he will almost cetainly feel a little more in control.
There is a toolkit you can download from this website on the home page, it can also be posted out to you if you want a printed copy. It is extremely comprehensive and covers all the terminology, stages of this cancer giving a good explanation about how a Gleason score is given, what the different stages are and all potential treatments etc. Maybe you can use it to help you and your OH to understand more so that you can help your FIL.
In the toolkit there is a good diagram of what a man's prostate is, where it is and what it should look like. He has only one, basically in a healthy adult male it is about the size of a walnut but smooth and soft. It has two mirror halves which is why you have heard descriptions of left and right prostate.
So as a first step get this official toolkit, do not rely on Google searches as they are way too generic when you are not entirely sure what your FIL's situation is. These searches often cause more worry and in some cases fear than is necessary.
If your FIL is ok with it make sure somebody goes with him to all his appointments so they can make notes and help him to ask questions to get clarification. It is really hard for anyone to remember every word that is said in these meetings and that extra support can be really valuable.
Others will also come along and post although it can sometimes take a day or so.
I wish you all the very best
xx
Mo