Question: "Brahman (the Self) is real, and the world is illusion" Yet others say,
"The world is reality." Which is true?

Sri Ramana Maharshi:

Both statements are true. They refer to different stages of development and are spoken from different points of view.

The aspirant starts with the definition: that which is real exists always. (does not change) Then he eliminates the world as unreal because it is changing.

The seeker ultimately reaches the Self and there finds unity as the prevailing note. Then, that which was originally rejected as being unreal is found to be a part of the unity.

Being absorbed in the reality, the world also is real. There is only being in
Self-realization, and nothing but being.