Firstly let us know why we use explode() function in php ?

explode() function basically used for breaking a string into an array in php. explode() function is binary-safe in php.

explode() function syntex is given bellow:

explode(',',string,0)

means there are three main important things in explode() function
1-separator(',')
2-string
3-limit

You can take reference form below example of explode() function in php.

?php
$Colorstr = 'red,blue,pink,green';
//here $Colorstr is a variable in which store all string of color name.

// now call explode() and give 0 limit
print_r(explode(',',$Colorstr,0));
print "<br-->";

//now call explode() and give positive limit 2
print_r(explode(',',$Colorstr,4));
?>

so when you will give limit 0 then output will come:

Array (
 [0] => red
          blue,pink,green
        )

and when you will give limit 4 then output will come:

Array (

[0] => red
[1] => blue
[2] => pink
[3] => green
      )