Learn Turkish: Fıstık sütünden başka üç tane içecek almamız lazım. - We need to buy three beverages besides the peanut milk.

It is required by the word başka. On its own, başka means 'other'. But when it follows a noun in the ablative case (-DAn), it becomes a postposition meaning 'besides', 'other than', or 'except'. Together, fıstık sütünden başka means 'besides the peanut milk'.

Where does the -n- come from in sütünden?

Fıstık sütü (peanut milk) is a noun compound. The -ü at the end is a possessive suffix linking the two words. In Turkish, whenever you attach a case suffix (like the ablative -den) to a word that already ends in a possessive suffix, you must use the buffer letter -n-.

How does almamız lazım mean 'we need to buy'?

To express 'need to' or 'have to', Turkish uses a verbal noun with a possessive suffix, followed by lazım (necessary). Almamız is formed from the verb al- (buy/take), the verbal noun suffix -ma, and the 'our' possessive suffix -mız. Literally, this translates to 'our buying is necessary'.

Is the word içecek related to the future tense?

Structurally, yes. The suffix -ecek is the future tense marker, but it is also frequently used to derive new nouns from verbs. Attached to iç- (to drink), it creates the noun içecek (beverage), literally meaning 'something that will be drunk'.