I found this sentence on tatoeba.org:
I just don't know what to say.
I understand most of the sentence, but what is "些" doing there? I've always seen it used to mean "a few".
You are correct, "些" is used to mean "a few" and it also applies in the example you gave above - ie. you can't even find 'a few' words to say.
I believe you can also leave out "些" and it will still mean almost the same thing. To me, with/without "些" the sentence means the same thing but has a slightly different emphasis/tone to it.
For me, with "些" it feels a bit 'softer'...as if you are genuinely out of words (maybe you saw something and suddenly lost for words); whilst without "些" it sounds like you are frustrated (someone has annoyed you, did something stupid) and you don't know how to comment/what to say to them.
ps. I would personally say:
pps. I'm also learning Chinese, so confirmation from someone who is a native speaker would be nice :)