Learn Turkish: Biz şimdi kasaba yürüyoruz. - We are walking to the butcher now.

The dictionary word for butcher is kasap. Because we are saying 'to the butcher', we add the direction suffix -a. In Turkish, when a word ends in a hard consonant like p and gets a suffix starting with a vowel, the p softens to a b. This is the consonant mutation rule you are learning right now!

What does the -a at the end of kasaba mean?

The suffix -a (which can also be -e depending on vowel harmony) shows direction and means 'to' or 'towards'. Adding it to the root word gives us the meaning 'to the butcher'.

Why does the personal ending on yürüyoruz use a u (-uz) when the verb root yürü has ü vowels?

This is a great vowel harmony refresher! The present continuous suffix -yor is special because its o never changes. Any suffix added after it must harmonize with that o, not the original verb root. Since o is followed by u in 4-way vowel harmony, the 'we' ending becomes -uz.

Could I put şimdi at the very beginning of the sentence?