Learn Farsi: پنج شش شاخه رز قرمز برای من بیاور.

Placing two consecutive numbers together like پنج شش (five six) is a standard way to express an estimated range in Farsi, meaning 'five or six'. You simply juxtapose them without needing to add یا (or) between them.

Even though we are asking for multiple roses, why is شاخه (stem) in the singular form?

In Farsi, a noun or measure word that follows a number must always remain singular. This rule strictly applies even when you are using an estimated range like پنج شش. Therefore, you must use the singular شاخه instead of the plural شاخه ها.

Is the word شاخه strictly necessary here, or could I just say پنج شش رز قرمز?

While dropping it would be understood, Farsi frequently uses measure words (counters) between numbers and nouns. شاخه literally means 'branch' and is the standard measure word for flowers. Using it makes your Farsi sound much more natural and native-like.

Why is the verb at the end بیاور instead of the shorter بیار that I usually hear?

بیاور is the standard written or formal imperative form of the verb آوردن (to bring). In everyday spoken Farsi, the 'v' is dropped, making it بیار. Both are completely correct, but بیاور gives the sentence a slightly more formal or literary tone.