what is a unit of speech that contains one unstressed syllable followed by stressed syllable?

A unit of speech that contains one unstressed syllable followed by a stressed syllable is called a trochee.

It's a type of metrical foot used in poetry and is often described as a "stressed-unstressed" pattern.

Here are some examples of trochees:

* Happy

* Never

* Garden

* Mountain

* Teacher

Let me know if you'd like to know more about poetic meter!