There are different interpretations on this, in Tafseer Al Tabari he interprets it as "the sun of the east does not touch it (the olive tree) nor does the sun of the west touch it"
( لا شَرْقِيَّةٍ وَلا غَرْبِيَّةٍ ) قال: فمثله مثل شجرة التفّ بها
الشجر، فهي خضراء ناعمة، لا تصيبها الشمس على أيّ حال كانت، لا إذا طلعت
ولا إذا غربت، وكذلك هذا المؤمن قد أجير من أن يصيبه شيء من الغير، وقد
ابتلي بها فثبته الله فيها، فهو بين أربع خلال: إن أعطي شكر، وإن ابتلي
صبر، وإن حكم عدل، وإن قال صدق، فهو في سائر الناس كالرجل الحيّ يمشي في
I can not translate this properly, so I am just going to translate what I can if someone can give a better translation please edit it:
A tree that is green and soft which the sun does not hit in what ever
state it is in, not when the sun comes up nor when it goes down. It
goes on to tell that this is the believer that has been saved from
something that would have tested him. It goes on to give four
"signs": If he was given something he thanked, if he was tested he was
patient, if you judged he was fair, if he talked he only said truth,
and he is in with people like a alive man walking among the graves of
In Tafseer Al Baghawee he interprets it as that the tree is not all eastern so when the sun goes down it does not hit the tree, and it is not all western so when the sun comes up in the east it does not hit the tree. So the tree is both eastern and western so it takes the sunlight from the two so the oil is more lighter or has more light. It is like the saying "he is not white or black" meaning he is not all white nor is he all black he is in between, I pray this helped to clarify it more Insha'Allah.
There are many other interpretations for this part of the Ayah in my opinion I think one should read all the tafaseers "At least the famous good ones :)" so that he can understand it from different views hence forming a view himself based on all the views he has read, that is my opinion.