Learn Farsi: گوشی ضد ضربه است و دو سال گارانتی دارد. - The phone is shockproof and has a two-year warranty.

The word zedd means opposite, anti-, or counter-, and zarbe means a blow, impact, or shock. Linked by an ezafe, zedd-e zarbe literally means anti-impact, which is the standard way to express shockproof or impact-resistant in Farsi.

Is the ezafe (the 'e' sound) connecting zedd and zarbe mandatory here?

Yes. Whenever you use zedd to form an 'anti-' or 'counter-' compound noun, you must use the ezafe to link it to the noun it modifies. It will always be pronounced zedd-e.

Why is the word for year (sâl) singular after the number two (do)?

This is a core Farsi rule that is easy to slip up on even at intermediate levels: nouns that follow a specific number always remain singular. So 'two years' is simply do sâl, never the plural do sâlhâ.

I recognize that gush means ear. How does it become the word for a phone?

Adding the suffix -i to a noun often creates a new object associated with that root. Gushi originally referred to an earpiece or telephone receiver. Today, it is the most common everyday word for a mobile phone.

Is gârânti a loanword, and is it standard to use over a native Farsi word?