Questions & Answers about Na deser kroję arbuza i ananasa na małe kawałki.
Because Polish often drops subject pronouns when they are already clear from the verb form. The ending -ę in kroję tells you it is 1st person singular, so I cut / I am cutting.
You could say Ja kroję..., but that would usually add emphasis, as in I’m the one cutting it.
This is an aspect question.
- kroić = imperfective
- pokroić = perfective
Kroję describes an action as ongoing, repeated, or simply viewed as a process:
I am cutting / I cut
Pokroję is perfective, so it usually refers to a completed action in the future:
I will cut up
So in this sentence, kroję is natural if the speaker is describing what they are doing now, or giving a recipe-like description.