A cell is a fully closed area in the model or cross-section geometry.
Cells in RFEM and RSTAB
If a surface is divided by internal lines, closed subsections are created within the surface. These regions are referred to as "surface cells".
Furthermore, "cells" in the model and load wizards allow for creating model objects and applying loads.
Cells in SHAPE-THIN
In the cross-section properties software SHAPE‑THIN, an area enclosed on all sides by elements is referred to as a "cell" in the cross-section geometry.
You can control the display of cells in Project Navigator - Display under "Model Data" → "Cells". If you deactivate the check box, this object will be hidden in the graphic.