Question

Help please I don't understand this stuff >.< (attachment)

Answer 1

If there were actual numbers at the ends of the line,
you'd have no trouble inventing some new numbers
that fit in the space between them.

OK.  Put actual numbers at the ends !
Pick up your calculator, and find the numbers for  √56  and  √58 .
You don't need them to be exact ... just keep a few decimal places.

       √56  =  7.483...

       √58  =  7.615...

There you are.  Now you have actual numbers at the ends
of that piece of number line in the question.  Now, can you
make up numbers that fit between them ? 

Here are a few that I invented: 

7.484
7.485
7.486
7.599
7.600
7.614

You should make your own. 
Don't worry about running out of numbers ...
there are an infinite number of them.