A decimal number can be defined as a number whose whole number part and the fractional part is separated by a decimal point.

Explanation: Let us discuss decimal.
A number whose decimal part and whole number part are separated by a point is called decimal.

For example, \$143.134\$.
Here, \$143\$ and \$134\$ are separated by a point. So, \$143.134\$ is a decimal number.

Subtracting decimals means finding the difference between decimal numbers.

Explanation: In this image we are subtracting two decimal numbers \$38.55\$ from \$22.32\$ we get \$16.23\$.