– Volume of a Fluid is measured in: L

– Volume of a Solid is measured in: m^3

– Mass is measured in: g

Here are a few examples of SI unit conversions, and what they mathematically mean (more can be found in the websites cited below):

1 L = 1000 ml

1 m = 100 cm = 1000 mm

1 g = 0.001 kg

Now regarding your question,

the base units of mass and volume are given above.

Density is the amount of mass per unit volume.

This means that: Density = Mass / Volume

Since mass is measured in [g] and volume is measured in either [L] (if it’s a fluid), or [m^3] (if it’s a solid), then:

Density = g/m^3 or g/L

You can, of course, apply prefixes to the base SI units, so the following is also true:

Density = g/cm^3 or g/ml, etc.