In simple way, as I have defined in earlier posts,
Real = That which is eternal and is present at all times. OR that which is no non-existence.
False = That which does not exist at any time.
False (asatya) cannot be experienced and hence the word 'asatya' is used only to complete duality i.e. fill pair of opposites.
MithyA = In between. That which is not eternal.
There can be two possibilities
1. The object is destroyed or of perishable nature, hence object after perishing leaves it's traces i.e. cloth burned by fire, reduces to ash, ashes are traces that once there was something.
2. Object after negation, does not leave a trace - snake does not leave any trace when rope is realized nor does silver leave trace when sea shell is realized nor is desert appearing as water.
So logically mithyA means illusion. But this contradicts our day-2-day perception. Hence there are 3 truths and it is said that this world is real from empherical POV and not from absolute POV.
The mithyAtva (property of this world being illusion) is only realized in samadhi and not before and hence as I have said, just saying everything is illusion and not doing anything is just empty talk.
The thing is that we are under ignorance and hence we see this (experience) this world. So efforts are to be mad to remove this ignorance or to transcend guNa-s, 3 states, 5 sheaths, etc. Since we are under ignorance, hence we have to accept this world as real, but at the same time, out attempts should be such that we cross the boundaries of guNa-s as our shruti-s teach.
Only after realization we can make such statements. For contemplation purpose, Self Enquiry, chanting OM or do neti-neti, all this accepts duality in the beginning, else there cannot be any sadhana, but the laxyArtha of such sadhana is to rise above guNa-s to experience ultimate truth.
So vAchyArtha is duality and talked in terms of duality.
laxyArtha is non-duality.
in short dual statements lead to non-duality.
We Adi shankara had not accepted 3 levels of truths, then we could accuse him and advaita as that which can never be started and that everything is illusion (at all levels) and that there is no guru, not sahdhana, no creation, etc.
But accepting 3 levels of truths makes advaita practical.