This is the 350th most frequent Polish word.
prostu
The Polish word "prostu" is a form of "prosty," meaning "simple" or "straight." In context, it can also mean "just" or "simply."
The phrase 'po prostu' is used here as an adverb meaning 'simply' to emphasize the adjective 'beautiful'.
To jest po prostu piękne.
This is simply beautiful.
The word 'prosto' means 'straight' in the context of directions.
Idź wzdłuż ulicy i potem prosto.
Walk along the street and then straight.
The form 'prost' (root of 'prostu') signifies clarity or simplicity in the context of explanation.