Dots appear above certain words in the chumash, a practice that corresponds to that of Alexandrian grammarians who used dots to indicate doubtful passages.
Why are there dots in the chumash, and what do they mean?
I have absolutely no idea, but here's one interesting view (among many) articulated by chazal:
"Ezra reasoned thus: If Elijah comes and asks me 'Why have you written these words?', I shall answer 'That is why I dotted the passages'. And if Elijah says to me 'You have done well in having written these passages' then I shall erase the dots over them." [Midrash Bamidbar Rabbah III.13 and Avot deRabbi Nathan 34]