Abu, is this the only error that you are getting? Usually, if intl is missing, other extensions can also be missing.
I am somewhat familiar with cPanel (on my GoDaddy servers.) There is a tool called "EasyApache4" or the older "EasyApache3". This is the tool that Bluehost might be referring to. See if you have it.
I must warn you that even though this tool has the word "Easy" in it, it may not be all that "easy" to use. Its a bit of t tricky utility, both #3 and #4. But this tool is probably easier to make these changes than using a terminal program (unless you are Howard and know what you are doing. )
If you find that intl is installed, you might need to enable it by uncommenting the appropriate line in your php.ini file.