You're likely thinking of the nucleus, not "nucleous". The nucleus is a very important organelle within a cell. Here's what it does:

* Stores the cell's genetic material (DNA): DNA contains the instructions for building and maintaining the entire organism.

* Controls cellular activities: The nucleus directs the synthesis of proteins, which carry out most of the cell's functions.

* Directs cell division: The nucleus ensures that each new cell receives a complete copy of the DNA.

* Protects the DNA: The nuclear membrane, a double membrane, surrounds the nucleus and helps protect the DNA from damage.

Essentially, the nucleus is the "brain" of the cell. It's the control center that dictates what the cell does and how it functions.