Welcome to the Q&A Forum

I am a little confused as to how search engines see and rank keywords. Let me explain. If I have a fairly long tail keyword such as "buy natural progesterone cream uk"  will the search engine also break this up into smaller parts such as "buy natural progesterone uk"," buy progesterone cream uk", "natural progesterone uk"  and so on or will it only see the words that are next to each other like "progesterone cream uk". Also where does cannibalization come into this? I really appreciate any help I can get with this that furthers my understanding. Thanks.