Questions & Answers about Po práci mám chvíli čas na procházku s rodinou.
The preposition po in the meaning “after (in time)” is followed by the locative case.
- The noun práce (work) has the locative form práci.
- So po práci literally means “after work (in the locative case)”.
You cannot say po práce here, because práce is not the locative form; po with time expressions needs the locative, so po práci is required.