Pitch is a voice quality produced by vibrations of the vocal folds.
Example
Many learners have a first language that is tonal, i.e. the same word said in a high pitch may mean something different from when it is said in a low pitch. Examples of tonal languages are Mandarin Chinese, Swedish and Scottish Gaelic. English is not a tonal language i.e. pitch changes in words do not change meanings. Patterns of pitch changes (intonation patterns) are used in English to indicate attitude.
In the classroom
Helping students to use intonation effectively to convey attitude in English will involve helping students to make the five tones (falls or rises in pitch): fall, rise, slight rise, fall followed by a rise, rise followed by a fall, through awareness raising and modelling of the common intonation patterns in context.
Further links:
https://www.teachingenglish.org.uk/article/intonation
https://www.teachingenglish.org.uk/article/teaching-speaking-unit-4-stress-intonation
https://www.teachingenglish.org.uk/article/gobbledygook
https://www.teachingenglish.org.uk/article/evaluating-speaking
https://www.teachingenglish.org.uk/article/reading-aloud