The term cell growth is used in the contexts of cell development and cell division (reproduction). When used in the context of cell division, it refers to growth of cell populations, where one cell (the "mother cell") grows and divides to produce two "daughter cells" (M phase). When used in the context of cell development, the term refers to increase in cytoplasmic and organelle volume (G1 phase), as well as increase in genetic material before replication (G2 phase).
Cell populations go through a particular type of exponential growth

Exponential growth

Exponential growth occurs when the growth rate of a mathematical function is proportional to the function's current value...

 called doubling.