The degree of force with which a speaker pronounces a sound or a syllable is called its stress.
Word Stress :
Primary & Secondary Stress:
If an English word has more than one syllable , one of them stands out, i.e. prominent . We say it with greater force of breath than other syllables and this syllable is said to have Word accent or primary stress:
A prominent syllable in a word other than the primary stress is said to have Secondary Stress.

 Primary Stress           -List of words (noun/ adjectives  )

 Noun /Adjective                        Verb 
 
 ‘rebel                                 re’bel

 ‘suspect                               sus’pect

 ‘contract                              con’tract 

 ‘object                                ob’ject 

 ‘import                                im’port 

 ‘conduct                               con’duct

 ‘convert                               con’cert 

Stress falls at different syllables depending upon the parts of speech they belong to. If a word is a noun or adjective , the stress falls on the first syllable , if it is used as a verb m then the stress is on the second syllable.
Sentence Stress
Content words and main verbs in a sentence are stressed.
Words may be classified in to Content words and Structural words. The former includes nouns, adjectives, verbs, and adverbs while the latter articles, prepositions , conjunctions, auxiliary verbs and pronouns.
In a sentence it is normally the content words that are stressed in speech . This phenomenon of certain types of words being more prominent than the rest is called Sentence Stress.

INTONATION :
When we speak, we use either the high pitch or the lower pitch and this variation in the pitch of our voice is called INTONATION.
The different patterns are known as Basis Patterns. They are the Fall, Rise, and Fall Rise patterns.