i  am  not  understanding  the  third  table  in  the  lesson  5  of  the  chapter  tenses  in  english

The third table also talks about future continuous tense. It informs us that when we describe any happening that would take place in the future or any event that would happen in the future, we write 'going' and add the base form of the next main verb to it. 

For instance,

- He is going to fast tomorrow morning.

- She is going to participate in debate.

- They are going to shift later next week.

- The building is going to collapse soon.

- It is going to rain.