Learn Turkish: Saat üçte markete git, kış için erzak alsan iyi olur. - Go to the supermarket at three o'clock; you had better buy provisions for the winter.

This is the structure you are currently learning for giving advice or making mild suggestions! Literally, it translates to 'If you buy, it becomes good.' It is formed by attaching the conditional suffix -sa and the personal ending -n (you) to the verb root al- (to buy/take), followed by iyi olur (it would be good).

Why doesn't the word erzak (provisions) have a plural suffix?

The word erzak already carries a collective or plural meaning, much like 'supplies' or 'provisions' in English. Because the word itself represents a plural concept, you don't need to add the plural suffix -lar to it.

Why are the two halves of this sentence separated only by a comma?

In Turkish, it is very common and grammatically correct to connect two related but independent clauses with just a comma. The first half is a direct command (markete git - go to the supermarket), and the second half gives the follow-up advice. While English often prefers a semicolon or a conjunction like 'and', a simple comma is perfectly natural here in Turkish.

As a quick refresher, why is it üçte instead of üçde?