Deductive Reasoning is part of smart logic such as the following :

Given below are a few examples that will help you understand this concept better:

All oranges are fruits

All fruits grow on trees

Therefore, all oranges grow on trees

Johnny is a bachelor,

All bachelors are single,

Hence, Johnny is single

The above examples are valid and sound. Here are a few valid, but unsound examples;

All flight attendants know how to swim

Ralph knows how to swim

Hence, Ralph is a flight attendant.