Hi @vijayolivefloor,
We have previously answered a similar query. Please refer to What is an API? - #3 by career_niecit2008. You can also refer to this workshop video https://www.boltiot.com/workshops?wchannelid=7pszk643nd&wmediaid=cew01q3y21 from 8:00 Timestamp.
Do let me know if you still do not understand.