Affricatives are consonant sounds made up of a stop, like /t/, immediately followed by a fricative, like /s/.

Example
The /tʃ/and /dʒ/ consonant sounds are affricatives.

In the classroom
The affricative sounds in English are common in other languages and relatively easy to produce for many learners.

Further links:

https://www.teachingenglish.org.uk/article/phonemic-chart