Here's a breakdown:

* Ribosomes are essential for protein synthesis. They read the genetic code from messenger RNA (mRNA) and assemble amino acids into proteins.

* The nucleolus is a dense region within the nucleus of eukaryotic cells. It's not bound by a membrane, but rather a collection of proteins and RNA.

* Within the nucleolus, ribosomal RNA (rRNA) is transcribed and assembled with proteins imported from the cytoplasm. This forms the subunits of ribosomes.

* These ribosomal subunits are then transported out of the nucleus into the cytoplasm, where they join together to form functional ribosomes.

So, the nucleolus is essentially the "factory" for producing ribosomes, the protein-building machines of the cell.