Learn Turkish: Lütfen caddede yavaş yürüyünüz. - Please walk slowly on the avenue.

The verb root is yürü (to walk). To make it a formal or plural command, we add the ending -ünüz. Because yürü ends in a vowel and the ending starts with a vowel, we add the buffer letter -y- in between to make it easier to say, giving us yürüyünüz.

What is the difference between saying yürüyün and yürüyünüz?

Both are polite, plural, or formal ways to say "walk!". yürüyün is the standard formal imperative you'd use with people you don't know well. Adding the extra -üz to make yürüyünüz makes it extremely formal. You will mostly see this longer form on official public signs or hear it in very formal announcements.

Yavaş usually means "slow". Why is it translated as "slowly" here?

In Turkish, you can often use an adjective directly as an adverb without adding any extra endings. Because yavaş is placed right before the verb yürüyünüz, it describes how the action is done, so it translates to "slowly".

What does the -de ending do in caddede?

The base word is cadde, which means "avenue" or "main street". The -de is the locative case ending, which translates to "in", "on", or "at". Together, caddede simply means "on the avenue".