Learn Turkish: Konuşmadan önce derin bir nefes alın. - Take a deep breath before speaking.

It uses the pattern for "before doing something". You take the verb root konuş- (speak) and add the suffix -madan (or -meden, based on vowel harmony). Finally, you add the word önce (before). Together, konuşmadan önce means "before speaking".

Doesn't the suffix -madan mean "without", as in "without speaking"?

Yes, exactly! On its own, konuşmadan means "without speaking". However, when it is immediately followed by önce, the combination specifically means "before speaking". This is the standard rule for saying "before doing [verb]" in Turkish.

Why is the word order derin bir nefes instead of bir derin nefes?

In English we say "a deep breath", but in Turkish, when an adjective (like derin) and the indefinite article bir both describe a noun, the adjective almost always comes first. The formula is Adjective + bir + Noun.

Why is the verb alın and not just al?

Alın is the formal or plural imperative (command) form of almak (to take). Adding the -ın suffix makes the instruction more polite, or shows it is directed at an audience of more than one person. If you were giving advice to a single close friend, you would just say al.