Questions & Answers about Es ist leicht zu verstehen.
What does "Es" refer to here? Is it necessary?
In Es ist leicht zu verstehen, es is a dummy subject (expletive) required by German main-clause word order. You cannot omit it: Ist leicht zu verstehen is ungrammatical. It corresponds to English dummy It in It is easy to understand.
Can I use "Das" instead of "Es"?
Yes, if you’re pointing to a specific thing just mentioned or visible: Das ist leicht zu verstehen. Es is generic/dummy; das refers to a concrete antecedent.
Why is "verstehen" at the end?
German main clauses are verb-second: the finite verb (ist) must be in position 2. Non-finite verb parts like zu verstehen go to the end, so you get Es | ist | leicht | zu verstehen.
Why "verstehen" (infinitive) and not "versteht"?
After zu, the verb stays in the infinitive: zu verstehen. You only conjugate the finite verb (ist here). Compare: Es ist schwer zu sagen, not Es ist schwer zu sagt.
Is "zu" here the same as the preposition "to"?