This is the definition of vacuoles.
A vacuole is a large single structure, of variable shape according to the cells, delimited by a lipid membrane called tonoplast. The vacuole concentrates 80 to 90% of the volume and weight of the plant cell. It contains mostly water, but also organic molecules such as carbohydrates, ions, pigments ...
The vacuole is the largest organelle of the plant cell; it is larger than the vacuoles of the other cells.
The vacuole mainly plays a role in maintaining cellular homeostasis, that is to say, it allows maintenance of the correct concentrations of the elements in the cytoplasm, by selectively storing elements within its membrane.
It also plays an important role in the turgescence of plant cells, by ensuring sufficient pressure inside the cell, to maintain rigidity of certain anatomical structures (stem).