Explain the relation between Liter,$d{m^3}$ and mL

Hint: litre is the unit of volume in the metric system which is equal to one cubic decimetre. Cubic decimeter is a metric unit of capacity, defined as the volume of one kilogram of pure water under standard conditions. One milliliter is equal to one thousandth of a liter, or 1 cubic centimeter.

Complete answer:
Kilogram was first established in 1795 as the mass of one cubic decimetre of water at the at the temperature of melting ice (\[0{\text{ }}^\circ C\]), one liter of liquid water has a mass of approximately precisely one kilogram. This connection is no longer precise due to subsequent redefinitions of the metre and kilogram.
A metric unit of volume, the liter (SI symbols L) is a metric unit of volume. 1 cubic decimetre ($d{m^3}$), 1000 cubic centimetres ($c{m^3}$), or 0.001 cubic metre (${m^3}$). A cubic decimetre (or liter) is equal to one-thousandth of a cubic meter and has a volume of 10 cm x 10 cm x 10 cm.
When measured at its maximum density, which occurs at around\[4{\text{ }}^\circ C\], one litre of water weighs approximately precisely one kilogramme. As a result, 1000th of a litre of water, also known as one millilitre (1 mL), has a mass of around 1 g, while 1000 litres of water has a mass of about 1000 kg (1 tonne or megagram). This connection holds because the gram was initially defined as the mass of 1 mL of water; however, because the density of water fluctuates with temperature and, very slightly, with pressure, this definition was abandoned in 1799.
We know that $1d{m^3} = 1L$
$1{\text{ }}d{m^3} = {(1 \times {10^{ - 1}}m)^3}$
Also
\[\;1L{\text{ }} \equiv {\text{ }}1\;d{m^3}\; \equiv {\text{ }}1000\;c{m^3} \equiv {10^6}ml\]
${\text{1ml = 1}}{{\text{0}}^{{\text{ - 3}}}}{\text{ L}}$
${\text{1L = 1000 ml}}$
Hence to conclude we can deduce the relationship as
${\text{1L = 1000 ml}}$ and $1d{m^3} = 1L$

Note:
Despite the fact that the litre is not an official SI unit, it can be used with SI prefixes. The millilitre, which is defined as one-thousandth of a litre and is also known by the SI derived unit name "cubic centimeter," is the most often used derived unit. It is a widely used unit of measurement in a variety of fields, including medical, cuisine, and automobile engineering.