what does _() and _e() means in wordpress 

What do the _() and _e() functions in WordPress do?

In WordPress, strings in the php files are marked for translation to other languages, and localization using two “tags” which are actually functions. They are:

_()
_e()

These accept a string as an argument. For example:

_(“Translate Me”)
_e(“Translate Me”)

The only functional difference between the two methods is that _e() echoes the string and _() simply returns the string. _() is used when you want to supply a string to a function. _e() is used when you want to output the string as part of your XHTML.