Explaination of Feedforward network in encoder and decoder

Ques. In attention is all you need lesson, the use of feed forward network in the encoder and decoder module is not quiet clear. It will be helpful if someone can explain it clearly. I did not understand the explaination given in the reading material too.

Link: https://www.coursera.org/learn/generative-ai-with-llms/lecture/R0xbD/generating-text-with-transformers