Questions & Answers about Proszę odejść od krawędzi peronu.
Why does the base verb iść become odejść instead of just odiść?
The prefix od- means 'away from'. When added to iść (to walk), an extra -e- is inserted to make it easier to pronounce, creating odejść. This is the perfective form, focusing on the completed action of stepping away.
Why do we see od in the verb and then again right after it?
This is a very common Polish pattern. Verbs of motion with the prefix od- (departing) are almost always followed by the preposition od (from) to introduce the exact thing you are moving away from.
What case is krawędzi and why?
It is in the Genitive case, because the preposition od always requires the Genitive. The base word is krawędź (edge). Even though it ends in a consonant, it is a feminine noun, and many feminine nouns ending in a soft consonant take -i in the Genitive.
Why is peronu also in the Genitive case? Is it because of od?
No, peronu is Genitive for a different reason. Here it shows possession or relation, translating to 'of the platform'. So you have od forcing krawędzi into the Genitive, and then the 'of' relationship forcing the masculine noun peron (platform) into the Genitive (peronu).