0x6b88 is a number in hexadecimal.
so _0x6b88 is like writing _27528, or myinteger. It is a variable name, the name doesn't really matter.
(_27528 is a different variable to _0x6b88, though)
It looks like an array, so lets replace it with alist to make it easier to understand:
$(alist[150])[alist[149]](); // runs an element with id alist[149]
$(alist[154])[alist[153]]( // runs an element and gives it a function
function () {
$(this)[alist[151]](alist[14]);
}
)
[alist[152]]( // gets an element from what ever is returned by the function
function () { // Passes a function to the element gotten
$(this)[alist[151]](alist8[12]);
}
);
alist[0] is the first element in the array. Inorder to work out what this does, you need to know what is in the cells of those arrays.
It is probably best to rewrite your code; it will be easier that way. It has been obfuscated, so you'll have a hard time working it out.
You probably won't be able to get the original variables names, although that depends on the software you used for obfuscating the code.