"Kde jíš?"

Translation: Where do you eat?

[MaryPuppo2]

The kde sounds just like Russian for the same word.

[VladaFu]

Given the common origin it is not too surprising. Or is it?

[.-o-__-o-.]

Yess, many words are very similar. "Kde jíš?" (czech) = "Gďe (ty) yesh?" (rus)

[EParrotta]

So the 'k' is pronounced 'g'?

[nueby]

I will answer here and delete the other places you ask. Yes, because the last consonant in the "kd" cluster is voiced, the voicing assimilation makes the "k" into a "g".