Transcription in prokaryotes occurs in the cytoplasm of the cell because prokaryotes lack membrane-bound nuclei. Since their DNA is not enclosed within a nucleus, the process of transcription (making RNA from DNA) happens directly in the cytoplasm where the DNA resides.
This is in contrast to eukaryotes, where transcription takes place inside the nucleus and the RNA then moves to the cytoplasm for translation. In prokaryotes, the processes of transcription and translation can even occur simultaneously in the cytoplasm.
Therefore, the location of transcription in prokaryotes is the cytoplasm, specifically in the region containing the DNA often called the nucleoid, which is not membrane-bound.